1
|
Bazer FW, Johnson GA. Early Embryonic Development in Agriculturally Important Species. Animals (Basel) 2024; 14:1882. [PMID: 38997994 PMCID: PMC11240814 DOI: 10.3390/ani14131882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/21/2024] [Accepted: 06/21/2024] [Indexed: 07/14/2024] Open
Abstract
The fertilization of oocytes ovulated by pigs, sheep, cows, and horses is not considered a limiting factor in successful establishment of pregnancy. Pig, sheep, and cow embryos undergo cleavage to the blastocyst stage, hatch from the zona pellucida, and undergo central-type implantation. Hatched blastocysts of pigs, sheep, and cows transition from tubular to long filamentous forms to establish surface area for exchange of nutrients and gases with the uterus. The equine blastocyst, surrounded by external membranes, does not elongate but migrates throughout the uterine lumen before attaching to the uterine luminal epithelium (LE) to begin implantation. Pregnancy recognition signaling in pigs requires the trophectoderm to express interleukin 1 beta, estrogens, prostaglandin E2, and interferon gamma. Sheep and cow conceptus trophectoderm expresses interferon tau that induces interferon regulatory factor 2 that inhibits transcription of estrogen and oxytocin receptors by uterine epithelia. This prevents oxytocin-induced luteolytic pulses of prostaglandin F2-alpha from regressing the corpora lutea, as well as ensuring the secretion of progesterone required for maintenance of pregnancy. The pregnancy recognition signal produced by equine blastocysts is not known. Implantation in these species requires interactions between extracellular matrix (ECM) proteins and integrins as the conceptus undergoes apposition and firm attachment to the uterine LE. This review provides details with respect to early embryonic development and the transition from spherical to filamentous conceptuses in pigs, sheep, and cows, as well as pre-implantation development of equine blastocysts and implantation of the conceptuses.
Collapse
Affiliation(s)
- Fuller W. Bazer
- Department of Animal Science, Texas A&M University, College Station, TX 77843-2471, USA
| | - Gregory A. Johnson
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-2471, USA;
| |
Collapse
|
2
|
Biase FH, Moorey SE, Schnuelle JG, Rodning S, Ortega MS, Spencer TE. Extensive rewiring of the gene regulatory interactions between in vitro-produced conceptuses and endometrium during attachment. PNAS NEXUS 2023; 2:pgad284. [PMID: 37711857 PMCID: PMC10498941 DOI: 10.1093/pnasnexus/pgad284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/22/2023] [Accepted: 08/25/2023] [Indexed: 09/16/2023]
Abstract
Pregnancy loss is a significant problem when embryos produced in vitro are transferred to a synchronized uterus. Currently, mechanisms that underlie losses of in vitro-produced embryos during implantation are largely unknown. We investigated this problem using cattle as a model of conceptus attachment by analyzing transcriptome data of paired extraembryonic membrane and endometrial samples collected on gestation days 18 and 25, which spans the attachment window in cattle. We identified that the transfer of an in vitro-produced embryo caused a significant alteration in transcript abundance of hundreds of genes in extraembryonic and endometrial tissues on gestation days 18 and 25, when compared to pregnancies initiated by artificial insemination. Many of the genes with altered transcript abundance are associated with biological processes that are relevant to the establishment of pregnancy. An integrative analysis of transcriptome data from the conceptus and endometrium identified hundreds of putative ligand-receptor pairs. There was a limited variation of ligand-receptor pairs in pregnancies initiated by in vitro-produced embryos on gestation day 18, and no alteration was observed on gestation day 25. In parallel, we identified that in vitro production of embryos caused an extensive alteration in the coexpression of genes expressed in the extraembryonic membranes and the corresponding endometrium on both gestation days. Both the transcriptional dysregulation that exists in the conceptus or endometrium independently and the rewiring of gene transcription between the conceptus and endometrium are a potential component of the mechanisms that contribute to pregnancy losses caused by in vitro production of embryos.
Collapse
Affiliation(s)
- Fernando H Biase
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Sarah E Moorey
- Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA
| | - Julie G Schnuelle
- Department of Clinical Sciences, Auburn University, Auburn, AL 36849, USA
| | - Soren Rodning
- Department of Animal Science, Auburn University, Auburn, AL 36849, USA
| | - Marta Sofia Ortega
- Department of Animal and Dairy Sciences, University of Wisconsin Madison, Madison, WI 53706, USA
| | - Thomas E Spencer
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
| |
Collapse
|
3
|
Du X, Liu Y, He X, Tao L, Fang M, Chu M. Uterus proliferative period ceRNA network of Yunshang black goat reveals candidate genes on different kidding number trait. Front Endocrinol (Lausanne) 2023; 14:1165409. [PMID: 37251683 PMCID: PMC10213787 DOI: 10.3389/fendo.2023.1165409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/13/2023] [Indexed: 05/31/2023] Open
Abstract
Pregnancy loss that occurs in the uterus is an important and widespread problem in humans and farm animals and is also a key factor affecting the fecundity of livestock. Understanding the differences in the fecundity of goats may be helpful in guiding the breeding of goats with high fecundity. In this study, we performed RNA sequencing and bioinformatics analysis to study the uterus of Yunshang black goats with high and low fecundity in the proliferative period. We identified mRNAs, long non-coding RNAs (lncRNAs), and microRNAs (miRNAs) by analyzing the uterine transcriptomes. The target genes of the identified miRNAs and lncRNAs were predicted, and miRNA-mRNA interaction and competitive endogenous RNA (ceRNA) networks were constructed. By comparisons between low- and high-fecundity groups, we identified 1,674 differentially expressed mRNAs (914 were upregulated, and 760 were downregulated), 288 differentially expressed lncRNAs (149 were upregulated, and 139 were downregulated), and 17 differentially expressed miRNAs (4 were upregulated, and 13 were downregulated). In addition, 49 miRNA-mRNA pairs and 45 miRNA-lncRNA pairs were predicted in the interaction networks. We successfully constructed a ceRNA interaction network with 108 edges that contained 19 miRNAs, 11 mRNAs, and 73 lncRNAs. Five candidate genes (PLEKHA7, FAT2, FN1, SYK, and ITPR2) that were annotated as cell adhesion or calcium membrane channel protein were identified. Our results provide the overall expression profiles of mRNAs, lncRNAs, and miRNAs in the goat uterus during the proliferative period and are a valuable reference for studies into the mechanisms associated with the high fecundity, which may be helpful to guide goat to reduce pregnancy loss.
Collapse
Affiliation(s)
- Xiaolong Du
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
- Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, Ministry of Agriculture and Rural Affairs (MARA) PRC Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Yufang Liu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaoyun He
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lin Tao
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Meiying Fang
- Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, Ministry of Agriculture and Rural Affairs (MARA) PRC Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Mingxing Chu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| |
Collapse
|
4
|
Davenport KM, Ortega MS, Johnson GA, Seo H, Spencer TE. Review: Implantation and placentation in ruminants. Animal 2023; 17 Suppl 1:100796. [PMID: 37567669 DOI: 10.1016/j.animal.2023.100796] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/26/2023] [Accepted: 03/27/2023] [Indexed: 08/13/2023] Open
Abstract
Ruminants have a unique placenta in comparison to other mammalian species. Initially, they possess a non-invasive epitheliochorial type of placenta during conceptus elongation. As the conceptus trophectoderm begins to attach to the luminal epithelium (LE) of the endometrium, binucleate cells (BNCs) develop within the trophoblast of the chorion. The BNCs migrate and fuse with the uterine LE to form multinucleate syncytial plaques in sheep and hybrid trinucleate cells in cattle. This area of the ruminant placenta is semi-invasive synepitheliochorial. The BNCs form the foundation of the placental cotyledons and express unique placenta-specific genes including pregnancy-associated glycoproteins and chorionic somatomammotropin hormone 2 or placental lactogen. Attachment and interdigitation of cotyledons into endometrial caruncles form placentomes that are subsequently vascularized to provide essential nutrients for growth of the fetus. This chapter review will discuss historical and current aspects of conceptus implantation and placenta development in ruminant ungulates with a focus on cattle and sheep. Single-cell analysis promises to provide a much more detailed understanding of the different cell populations and insights into pathways mediating trophoblast and placenta. This fundamental is required to understand pregnancy loss and develop strategies to improve pregnancy outcomes in ruminants.
Collapse
Affiliation(s)
- K M Davenport
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
| | - M S Ortega
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - G A Johnson
- Department of Veterinary Integrative Biosciences and Department of Animal Science, Texas A&M University, College Station, TX 7784, USA
| | - H Seo
- Department of Veterinary Integrative Biosciences and Department of Animal Science, Texas A&M University, College Station, TX 7784, USA
| | - T E Spencer
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA; Division of Obstetrics, Gynecology, and Women's Health, University of Missouri, Columbia, MO 65211, USA.
| |
Collapse
|
5
|
Pursley JR, Santos A, Minela T. Review: Initial increase in pregnancy-specific protein B in maternal circulation after artificial insemination is a key indicator of embryonic survival in dairy cows. Animal 2023; 17 Suppl 1:100746. [PMID: 37567663 DOI: 10.1016/j.animal.2023.100746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 08/13/2023] Open
Abstract
Lactating dairy cows have reduced chances for pregnancy survival following 1st parturition. It appears that timing of conceptus attachment, defined as an initial daily rise in pregnancy-specific protein B (PSPB) postartificial insemination (AI), is key to the survival of the embryo. PSPB is a protein produced from binucleate cells of the trophectoderm of the conceptus. Once the conceptus has attached to the uterine epithelial cells, this large protein is detectable in maternal circulation. Daily sampling of serum allows for detection of the initial increase of PSPB. A percent increase threshold for PSPB was determined from results from each study using a conservative three-day minimum increase. Thus far, a 10 or 12.5% daily increase for three consecutive days had the greatest sensitivities and specificities for studies reported in this review. Nulliparous heifers receiving AI following estrus appear to have a reduced time to conceptus attachment compared to lactating cows that received either Ovsynch or AI following estrus. Increasing progesterone post-AI did not reduce time to conceptus attachment in lactating cows. Multiparous cows treated post-AI with human chorionic gonadotropin had a reduced percent with conceptus attachment in addition to greater time to conceptus attachment. Increased time to conceptus attachment increased the chances of multiparous cows having embryonic death before 35 d post-AI. Concentrations of PSPB are consistently reduced from conceptus attachment until d 28 post-AI in cows with pregnancy loss compared to cows that maintain pregnancy on d 34 post-AI. This novel model to determine timing of conceptus attachment provides a new perspective on percent of cows pregnant around d 20-23 post-AI and the potential for a greater understanding of subsequent pregnancy loss.
Collapse
Affiliation(s)
- J R Pursley
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA.
| | - Alisson Santos
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - Thainá Minela
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| |
Collapse
|
6
|
Santos A, Minela T, Branen J, Pursley JR. Time to increase in pregnancy-specific protein B following artificial insemination is a direct determinant of subsequent pregnancy loss in lactating dairy cows. J Dairy Sci 2023; 106:3734-3747. [PMID: 37028965 DOI: 10.3168/jds.2022-22553] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 12/15/2022] [Indexed: 04/09/2023]
Abstract
Increasing progesterone (P4) during early conceptus development may be crucial for establishment of pregnancy in dairy cattle. The objective of this study was to determine if human chorionic gonadotropin (hCG) at various times after ovulation will increase serum P4 during elongation and increase the chances for, and reduce variability to, initial increase in pregnancy-specific protein B (PSPB) following artificial insemination (AI). Time to PSPB increase was defined as the first day of increase in concentrations of PSPB between d 18 and 28 after ovulation in cows with ≥12.5% increases for 3 consecutive days compared with baseline. Lactating cows (n = 368) synchronized to Double-Ovsynch (first service) or Ovsynch (second or greater service) received one of 4 treatments: no hCG (control), or 3,000 IU of hCG on d 2 (D2), 2 and 5 (D2+5), or 5 (D5) after ovulation. All cows were examined via ultrasound on d 5 and 10 postovulation to determine percentage of cows with hCG-induced accessory CL (aCL) and to quantify and measure all luteal structures. Samples for serum P4 were collected on d 0, 5, 19, and 20 postovulation. The P4 was increased in D2, D2+5, and D5 groups compared with control. The D2+5 and D5 treatments increased aCL and P4 compared with D2 and control. The D2 treatment increased P4 on d 5 after ovulation compared with control. Serum PSPB samples were collected daily from all cows on d 18 through 28 after ovulation for determination of d of PSPB increase. Pregnancy diagnoses were performed via ultrasound examination on d 35, 63, and 100 after ovulation and AI. The D5 treatment reduced percentage of cows with, and increased the time to, PSPB increase. Primiparous cows with ipsilateral aCL had reduced pregnancy loss before d 100 postovulation compared with cows with contralateral aCL. Cows that had PSPB increase >21 d postovulation had 4× greater chances of pregnancy loss compared with cows that had PSPB increase on d 20 or 21. The highest quartile of P4 on d 5, but not on d 19 and 20, was associated with reduced time to PSPB increase. Time to PSPB increase appears to be an important measurement to understand reasons for pregnancy loss in lactating dairy cows. Increasing P4 utilizing hCG after ovulation did not enhance early pregnancy or reduce pregnancy losses in lactating dairy cows.
Collapse
Affiliation(s)
- A Santos
- Department of Animal Science, Michigan State University, East Lansing 48824
| | - T Minela
- Department of Animal Science, Michigan State University, East Lansing 48824
| | - J Branen
- BioTracking Inc., Moscow, ID 83843
| | - J R Pursley
- Department of Animal Science, Michigan State University, East Lansing 48824.
| |
Collapse
|
7
|
Middleton E, Minela T, Ahearne M, Arnold H, Santos A, Pursley J. Dairy heifers have an earlier increase in serum pregnancy-specific protein B compared with lactating dairy cows. Is this an indicator of earlier conceptus attachment? JDS COMMUNICATIONS 2022; 3:291-295. [PMID: 36338019 PMCID: PMC9623710 DOI: 10.3168/jdsc.2021-0198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/27/2022] [Indexed: 06/16/2023]
Abstract
This study was designed to use within-individual daily increases in circulating pregnancy-specific protein B (PSPB) to determine time to increase in serum PSPB in nulliparous heifers and multiparous dairy cows following artificial insemination (AI). Weekly cohorts of lactating Holstein cows (n = 56) averaging 122 ± 7 d in milk at AI and nulliparous Holstein heifers (n = 23) averaging 16 ± 0.24 mo old at AI were used in this study. Lactating cows received AI to either Ovsynch (n = 38) or at ~12 h following observed standing estrus (n = 18). All heifers were inseminated ~12 h after observed standing estrus. Blood samples for measurement of PSPB were collected daily from d 15 through d 35 postovulation. Nulliparous heifers had increases in serum PSPB earlier compared with both primiparous and multiparous cows. Day of increase in serum PSPB was defined as the day serum PSPB optical density levels initially increased ≥10% from baseline and continued to increase from baseline of ≥10% the following 2 d. Average PSPB were greater in pregnant heifers compared pregnant cows from d 23 through 29. Early lactation nonpregnant cows maintained greater average optical density of serum PSPB from 15 to 35 d postovulation compared with nonpregnant heifers (n = 38). In summary, fertility differences in heifers versus lactating cows may be due to the differences in timing of increases in serum PSPB. This appears to be one of the first publications that used daily PSPB sampling to investigate possible differences in fertility in heifers versus lactating cows.
Collapse
|
8
|
Green JA, Geisert RD, Johnson GA, Spencer TE. Implantation and Placentation in Ruminants. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2022; 234:129-154. [PMID: 34694480 DOI: 10.1007/978-3-030-77360-1_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
In comparison to many other mammalian species, ruminant ungulates have a unique form of placentation. Ruminants initially display an epitheliochorial type of placentation; however, during the period of placental attachment, trophoblast giant binucleate cells (BNC) develop within the chorion to migrate and fuse with the uterine surface epithelium to form syncytial plaques. Binucleate cell migration and fusion continues throughout pregnancy but never appears to breach the basal lamina, beneath the uterine surface or luminal epithelium. Therefore, the semi-invasive type of placentation in ruminants is classified as synepitheliochorial. The endometrium of ruminant species also contains unique specialized aglandular structures termed "caruncles" in which the chorioallantois (cotyledons) interdigitates and forms highly vascularized fetal-maternal "placentomes." This chapter will discuss the current knowledge of early conceptus development during the peri-attachment period, establishment of pregnancy, conceptus attachment, and placentation in ruminant ungulates. The features of placentomes, BNCs, fetomaternal hybrid cells, and multinucleated syncytial plaques of the cotyledonary placenta of ruminant species will be reviewed to highlight the unique form of placentation compared to the placentae of other artiodactyls.
Collapse
Affiliation(s)
- Jonathan A Green
- Division of Animal Sciences, College of Agriculture, Food, Natural Resources, S138 Animal Science Research Center, University of Missouri, Columbia, MO, USA.
| | - Rodney D Geisert
- Division of Animal Sciences, College of Agriculture, Food, Natural Resources, S121 Animal Science Research Center, University of Missouri, Columbia, MO, USA
| | - Greg A Johnson
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Thomas E Spencer
- Division of Animal Sciences, College of Agriculture, Food, Natural Resources, S135 Animal Science Research Center, University of Missouri, Columbia, MO, USA
| |
Collapse
|
9
|
Dudley JS, Murphy CR, Thompson MB, McAllan BM. Uterine cellular changes during mammalian pregnancy and the evolution of placentation. Biol Reprod 2021; 105:1381-1400. [PMID: 34514493 DOI: 10.1093/biolre/ioab170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/25/2021] [Accepted: 09/06/2021] [Indexed: 11/14/2022] Open
Abstract
There are many different forms of nutrient provision in viviparous (live bearing) species. The formation of a placenta is one method where the placenta functions to transfer nutrients from mother to fetus (placentotrophy), transfer waste from the fetus to the mother and respiratory gas exchange. Despite having the same overarching function, there are different types of placentation within placentotrophic vertebrates, and many morphological changes occur in the uterus during pregnancy to facilitate formation of the placenta. These changes are regulated in complex ways but are controlled by similar hormonal mechanisms across species. This review describes current knowledge of the morphological and molecular changes to the uterine epithelium preceding implantation among mammals. Our aim is to identify the commonalities and constraints of these cellular changes to understand the evolution of placentation in mammals and propose directions for future research. We compare and discuss the complex modifications to the ultrastructure of uterine epithelial cells and show that there are similarities in the changes to the cytoskeleton and gross morphology of the uterine epithelial cells, especially of the apical and lateral plasma membrane of the cells during the formation of a placenta in all eutherians and marsupials studied to date. We conclude that further research is needed to understand the evolution of placentation among viviparous mammals, particularly concerning the level of placental invasiveness, hormonal control and genetic underpinnings of pregnancy in marsupial taxa.
Collapse
Affiliation(s)
- Jessica S Dudley
- School of Life and Environmental Science, University of Sydney, Sydney, NSW 2006, Australia.,School of Medical Sciences and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia.,Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, NSW, 2109, Australia
| | - Christopher R Murphy
- School of Medical Sciences and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia
| | - Michael B Thompson
- School of Life and Environmental Science, University of Sydney, Sydney, NSW 2006, Australia
| | - Bronwyn M McAllan
- School of Life and Environmental Science, University of Sydney, Sydney, NSW 2006, Australia.,School of Medical Sciences and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia
| |
Collapse
|
10
|
Chankeaw W, Lignier S, Richard C, Ntallaris T, Raliou M, Guo Y, Plassard D, Bevilacqua C, Sandra O, Andersson G, Humblot P, Charpigny G. Analysis of the transcriptome of bovine endometrial cells isolated by laser micro-dissection (1): specific signatures of stromal, glandular and luminal epithelial cells. BMC Genomics 2021; 22:451. [PMID: 34139994 PMCID: PMC8212485 DOI: 10.1186/s12864-021-07712-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 04/11/2021] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND A number of studies have examined mRNA expression profiles of bovine endometrium at estrus and around the peri-implantation period of pregnancy. However, to date, these studies have been performed on the whole endometrium which is a complex tissue. Consequently, the knowledge of cell-specific gene expression, when analysis performed with whole endometrium, is still weak and obviously limits the relevance of the results of gene expression studies. Thus, the aim of this study was to characterize specific transcriptome of the three main cell-types of the bovine endometrium at day-15 of the estrus cycle. RESULTS In the RNA-Seq analysis, the number of expressed genes detected over 10 transcripts per million was 6622, 7814 and 8242 for LE, GE and ST respectively. ST expressed exclusively 1236 genes while only 551 transcripts were specific to the GE and 330 specific to LE. For ST, over-represented biological processes included many regulation processes and response to stimulus, cell communication and cell adhesion, extracellular matrix organization as well as developmental process. For GE, cilium organization, cilium movement, protein localization to cilium and microtubule-based process were the only four main biological processes enriched. For LE, over-represented biological processes were enzyme linked receptor protein signaling pathway, cell-substrate adhesion and circulatory system process. CONCLUSION The data show that each endometrial cell-type has a distinct molecular signature and provide a significantly improved overview on the biological process supported by specific cell-types. The most interesting result is that stromal cells express more genes than the two epithelial types and are associated with a greater number of pathways and ontology terms.
Collapse
Affiliation(s)
- Wiruntita Chankeaw
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, SLU, PO Box 7054, 750 07, Uppsala, Sweden
- Faculty of Veterinary Science, Rajamangala University of Technolgy Srivijaya (RUTS), Thungyai, Nakhon si thammarat, 80240, Thailand
| | - Sandra Lignier
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
| | - Christophe Richard
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
| | - Theodoros Ntallaris
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, SLU, PO Box 7054, 750 07, Uppsala, Sweden
| | - Mariam Raliou
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
| | - Yongzhi Guo
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, SLU, PO Box 7054, 750 07, Uppsala, Sweden
| | - Damien Plassard
- GenomEast Platform CERBM GIE, IGBMC, 67404, Illkirch, Cedex, France
| | - Claudia Bevilacqua
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350, Jouy en Josas, France
| | - Olivier Sandra
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
| | - Göran Andersson
- Department of Animal Breeding and Genetics, Molecular Genetics, Swedish University of Agricultural Sciences, SLU, PO Box 7023, 750 07, Uppsala, Sweden
| | - Patrice Humblot
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, SLU, PO Box 7054, 750 07, Uppsala, Sweden
| | - Gilles Charpigny
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France.
- Department of Animal Breeding and Genetics, Molecular Genetics, Swedish University of Agricultural Sciences, SLU, PO Box 7023, 750 07, Uppsala, Sweden.
| |
Collapse
|
11
|
Kumro FG, O'Neil EV, Ciernia LA, Moraes JGN, Spencer TE, Lucy MC. Scanning electron microscopy of the surface epithelium of the bovine endometrium. J Dairy Sci 2020; 103:12083-12090. [PMID: 32981737 DOI: 10.3168/jds.2020-18852] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/15/2020] [Indexed: 11/19/2022]
Abstract
The surface epithelium of the bovine endometrium comprises at least 2 cell types (ciliated cells and secretory cells with microvilli), but their distribution and morphological changes over the estrous cycle are poorly understood. The objective was to quantify the number of ciliated cells and assess morphological changes in secretory cells on the uterine surface epithelium during the estrous cycle. Caruncular endometrium (CAR) and intercaruncular endometrium (ICAR) samples were collected from the uterine body, the horn ipsilateral to the corpus luteum or dominant follicle (H-CL/DF), and the horn contralateral to the corpus luteum or dominant follicle (H-NCL/NDF) from heifers following slaughter on d 0 (estrus; n = 5) or d 14 (mid-luteal phase; n = 5) of the estrous cycle. Samples were prepared for scanning electron microscopy at 1,000× magnification. Four to 10 fields (256 × 225 µm) for each sample were examined (n = 567 images). The number of ciliated cells was counted and the surface was scored for the morphology of the secretory cells (0 = absence of microvilli on surface; 3 = 100% of surface covered with microvilli). Ciliated cells were present in both the CAR and ICAR regions. The number of ciliated cells per field increased from d 0 to 14 in CAR and decreased from d 0 to14 in ICAR. The scanning electron microscopy revealed a general lack of uniformity in the lawn of microvilli on the surface of the endometrium. Based on the scores, approximately 25% of the fields had a surface that was <50% covered by microvilli. Depletion of microvilli may be explained by a normal process where apical protrusions are formed and either regress back into the cell surface or break to release their contents into the uterine lumen. These studies support the hypothesis that the surface of the luminal epithelium changes during the estrous cycle through a process that involves remodeling of the apical surface. The morphology of the apical surface may have a key role in governing pregnancy establishment.
Collapse
Affiliation(s)
- F G Kumro
- Division of Animal Sciences, University of Missouri, Columbia 65211
| | - E V O'Neil
- Division of Animal Sciences, University of Missouri, Columbia 65211
| | - L A Ciernia
- Division of Animal Sciences, University of Missouri, Columbia 65211
| | - J G N Moraes
- Division of Animal Sciences, University of Missouri, Columbia 65211
| | - T E Spencer
- Division of Animal Sciences, University of Missouri, Columbia 65211
| | - M C Lucy
- Division of Animal Sciences, University of Missouri, Columbia 65211.
| |
Collapse
|
12
|
Pfeffer PL. Building Principles for Constructing a Mammalian Blastocyst Embryo. BIOLOGY 2018; 7:biology7030041. [PMID: 30041494 PMCID: PMC6164496 DOI: 10.3390/biology7030041] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 07/19/2018] [Accepted: 07/20/2018] [Indexed: 12/16/2022]
Abstract
The self-organisation of a fertilised egg to form a blastocyst structure, which consists of three distinct cell lineages (trophoblast, epiblast and hypoblast) arranged around an off-centre cavity, is unique to mammals. While the starting point (the zygote) and endpoint (the blastocyst) are similar in all mammals, the intervening events have diverged. This review examines and compares the descriptive and functional data surrounding embryonic gene activation, symmetry-breaking, first and second lineage establishment, and fate commitment in a wide range of mammalian orders. The exquisite detail known from mouse embryogenesis, embryonic stem cell studies and the wealth of recent single cell transcriptomic experiments are used to highlight the building principles underlying early mammalian embryonic development.
Collapse
Affiliation(s)
- Peter L Pfeffer
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand.
| |
Collapse
|
13
|
Smith MF, Geisert RD, Parrish JJ. Reproduction in domestic ruminants during the past 50 yr: discovery to application. J Anim Sci 2018; 96:2952-2970. [PMID: 29684167 PMCID: PMC6095338 DOI: 10.1093/jas/sky139] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 04/18/2018] [Indexed: 12/18/2022] Open
Abstract
The study of reproductive physiology in domestic ruminants has progressed from the whole animal to the molecular level in an amazingly short period of time. The volume of information on this subject is enormous; therefore, we have focused on domestic ruminants, with an emphasis on cattle. To date, artificial insemination (AI) is perhaps the most powerful technique that reproductive physiologists and geneticists have provided the livestock industry for genetic improvement. Early efforts to establish AI as a tool were initiated in Russia around 1899 and since that time major advances in methods of semen collection, evaluation of male fertility, cryopreservation of sperm, sex-sorted semen, and estrous cycle control have occurred. The preceding advances not only led to the widespread use of AI, but also contributed to our fundamental understanding of ovulation control, timing of insemination, gamete biology, and cryopreservation. In regards to anestrus, our understanding of the concept of neuroendocrine control of the pituitary gland and the role of steroid feedback led to the Gonadostat Theory, which proposes that onset of puberty is due to a decrease in the negative feedback of gonadal steroids over time. Subsequent studies in prepuberal and postpartum sheep and cattle established that a short luteal phase frequently precedes the first normal length cycle that is accompanied by estrous expression. This observation led to the common practice of treating prepuberal heifers and anestrous postpartum cows with a short-term progestin treatment (e.g., Controlled Internal Drug Release) to induce normal estrous cycles. In domestic ruminants, fertilization rate is high (85% to 95%); however, significant embryonic mortality before or around the time of maternal recognition of pregnancy (MRP) reduces the pregnancy rate to a single breeding. Significant effort has been directed at determining the time of MRP, the signal for MRP, as well as elucidating the physiological, cellular, and molecular dialogue between the conceptus and uterine environment. Advancements have now led us to the ability to edit the genome to alleviate disease and possibly improve production traits. In summary, major advancements in our understanding of reproductive biology have stemmed from efforts to establish the AI and embryo transfer technique and reduce the negative impact of anestrus and embryonic mortality in domestic ruminants.
Collapse
Affiliation(s)
- Michael F Smith
- Division of Animal Science, University of Missouri, Columbia, MO
| | - Rodney D Geisert
- Division of Animal Science, University of Missouri, Columbia, MO
| | - John J Parrish
- Department of Animal Science, University of Wisconsin, Madison, WI
| |
Collapse
|
14
|
Graubner FR, Gram A, Kautz E, Bauersachs S, Aslan S, Agaoglu AR, Boos A, Kowalewski MP. Uterine responses to early pre-attachment embryos in the domestic dog and comparisons with other domestic animal species. Biol Reprod 2018. [PMID: 28651344 PMCID: PMC5803782 DOI: 10.1093/biolre/iox063] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In the dog, there is no luteolysis in the absence of pregnancy. Thus, this species lacks any anti-luteolytic endocrine signal as found in other species that modulate uterine function during the critical period of pregnancy establishment. Nevertheless, in the dog an embryo-maternal communication must occur in order to prevent rejection of embryos. Based on this hypothesis, we performed microarray analysis of canine uterine samples collected during pre-attachment phase (days 10-12) and in corresponding non-pregnant controls, in order to elucidate the embryo attachment signal. An additional goal was to identify differences in uterine responses to pre-attachment embryos between dogs and other mammalian species exhibiting different reproductive patterns with regard to luteolysis, implantation, and preparation for placentation. Therefore, the canine microarray data were compared with gene sets from pigs, cattle, horses, and humans. We found 412 genes differentially regulated between the two experimental groups. The functional terms most strongly enriched in response to pre-attachment embryos related to extracellular matrix function and remodeling, and to immune and inflammatory responses. Several candidate genes were validated by semi-quantitative PCR. When compared with other species, best matches were found with human and equine counterparts. Especially for the pig, the majority of overlapping genes showed opposite expression patterns. Interestingly, 1926 genes did not pair with any of the other gene sets. Using a microarray approach, we report the uterine changes in the dog driven by the presence of embryos and compare these results with datasets from other mammalian species, finding common-, contrary-, and exclusively canine-regulated genes.
Collapse
Affiliation(s)
- Felix R Graubner
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Aykut Gram
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Ewa Kautz
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Stefan Bauersachs
- Institute of Agricultural Sciences, Animal Physiology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Selim Aslan
- Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Near East University, Nicosia, North Cyprus
| | - Ali R Agaoglu
- Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Mehmet Akif Ersoy University, Burdur, Turkey
| | - Alois Boos
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Mariusz P Kowalewski
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| |
Collapse
|
15
|
The newly established bovine endometrial gland cell line (BEGC) forms gland acini in vitro and is only IFNτ-responsive (MAPK42/44 activation) after E 2 and P 4-pre-incubation. Placenta 2018; 67:61-69. [PMID: 29941175 DOI: 10.1016/j.placenta.2018.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 05/15/2018] [Accepted: 05/21/2018] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Uterine glands (UG) are crucial for the establishment of ruminant pregnancy and influenced (orchestrated manner) by estrogen (E2), progesterone (P4) and interferon tau (IFNτ). In the study we established a bovine endometrial glandular cell line (BGEC) and tested its functional reactivity (signaling) to IFNτ. METHODS BGEC was characterized by light microscopy (LM), epithelial markers (ezrin, CK18) [immunofluorescence (IF)/immunohistochemistry (IHC)] and ultrastructure (TEM/SEM) (apical microvilli). In vitro formation of gland acini and transepithelial-electric-resistance (TEER) measurements (EVOM) were done. The expression of mRNA-transcripts (RT-PCR) of steroid receptors (PR, PGRMC1/2, ESR1/2) and the IFNτ-system (IFNAR1/2, IRF1, 2, 9) was checked. BEGC was stimulated with IFNτ (10 ng/ml;1000 ng/ml) (15 min) after steroid pre-treatment [10 pg/ml E2 (two days)/20 ng/ml P4 (two days)]. Activation of MAPK42/44;STAT1 was evaluated (densitometrical Western Blot). RESULTS BGEC cells expressed epithelial markers and possessed apical microvilli. High TEER-values could be measured (2320-2620 ohm/cm2). The assembled BEGC acini (25 days) were similar to UG in vivo (markers/ultrastructure). All transcripts (steroid receptors/IFNτ-system) could be detected in BEGC (mRNA). MAPK42/44 were significantly activated after E2/P4 pre-treatment and IFNτ stimulation (10 ng/ml) (p < 0.05), whilst 1000 ng/ml IFNτ did not activate MAPK42/44. Neither a STAT1 (by IFNτ) nor an activation (MAPK42/44;STAT1) by IFNτ-only was observed. DISCUSSION BGEC retains its epithelial phenotype in culture and forms gland acini in vitro thereby confirming its glandular character. Cells were only reactive to (low) IFNτ concentrations when pre-treated with steroids thereby closely resembling implantation physiology in vivo. BEGC can be used as a bovine implantation model to study embryo-maternal communication during early pregnancy in cattle.
Collapse
|
16
|
Bazer FW, Wang X, Johnson GA, Wu G. Select nutrients and their effects on conceptus development in mammals. ACTA ACUST UNITED AC 2015; 1:85-95. [PMID: 29767122 PMCID: PMC5945975 DOI: 10.1016/j.aninu.2015.07.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 07/30/2015] [Indexed: 11/30/2022]
Abstract
The dialogue between the mammalian conceptus (embryo/fetus and associated membranes) involves signaling for pregnancy recognition and maintenance of pregnancy during the critical peri-implantation period of pregnancy when the stage is set for implantation and placentation that precedes fetal development. Uterine epithelial cells secrete and/or transport a wide range of molecules, including nutrients, collectively referred to as histotroph that are transported into the fetal-placental vascular system to support growth and development of the conceptus. The availability of uterine-derived histotroph has long-term consequences for the health and well-being of the fetus and the prevention of adult onset of metabolic diseases. Histotroph includes numerous amino acids, but arginine plays a particularly important role as a source of nitric oxide and polyamines required for fetal-placental development in rodents, swine and humans through mechanisms that remain to be fully elucidated. Mechanisms whereby arginine regulates expression of genes via the mechanistic target of rapamycin cell signaling pathways critical to conceptus development, implantation and placentation are discussed in detail in this review.
Collapse
Affiliation(s)
- Fuller W Bazer
- Departments of Animal Science, Texas A&M University, College Station, TX 77843-2471, USA
| | - Xiaoqiu Wang
- Departments of Animal Science, Texas A&M University, College Station, TX 77843-2471, USA
| | - Greg A Johnson
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA
| | - Guoyao Wu
- Departments of Animal Science, Texas A&M University, College Station, TX 77843-2471, USA
| |
Collapse
|
17
|
Spencer TE, Hansen TR. Implantation and Establishment of Pregnancy in Ruminants. REGULATION OF IMPLANTATION AND ESTABLISHMENT OF PREGNANCY IN MAMMALS 2015; 216:105-35. [DOI: 10.1007/978-3-319-15856-3_7] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
18
|
Abstract
There is a dialogue between the developing conceptus (embryo-fetus and associated placental membranes) and maternal uterus which must be established during the peri-implantation period for pregnancy recognition signaling, implantation, regulation of gene expression by uterine epithelial and stromal cells, placentation and exchange of nutrients and gases. The uterus provide a microenvironment in which molecules secreted by uterine epithelia or transported into the uterine lumen represent histotroph required for growth and development of the conceptus and receptivity of the uterus to implantation. Pregnancy recognition signaling mechanisms sustain the functional lifespan of the corpora lutea (CL) which produce progesterone, the hormone of pregnancy essential for uterine functions that support implantation and placentation required for a successful outcome of pregnancy. It is within the peri-implantation period that most embryonic deaths occur due to deficiencies attributed to uterine functions or failure of the conceptus to develop appropriately, signal pregnancy recognition and/or undergo implantation and placentation. With proper placentation, the fetal fluids and fetal membranes each have unique functions to ensure hematotrophic and histotrophic nutrition in support of growth and development of the fetus. The endocrine status of the pregnant female and her nutritional status are critical for successful establishment and maintenance of pregnancy. This review addresses the complexity of key mechanisms that are characteristic of successful reproduction in sheep and pigs and gaps in knowledge that must be the subject of research in order to enhance fertility and reproductive health of livestock species.
Collapse
|
19
|
|
20
|
Igwebuike UM. A review of uterine structural modifications that influence conceptus implantation and development in sheep and goats. Anim Reprod Sci 2008; 112:1-7. [PMID: 19162416 DOI: 10.1016/j.anireprosci.2008.12.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 12/01/2008] [Accepted: 12/10/2008] [Indexed: 10/21/2022]
Abstract
Evolution of the placenta and viviparity in eutherian animals underscores the need for an intimate relationship between the developing conceptus (embryo/foetus and associated extra-embryonic membranes) and the dam throughout the period of pregnancy. Thus, maternal support is unequivocally important for conceptus survival and development in utero. Under the influence of several pregnancy-associated hormones, the maternal uterine architecture undergoes rapid growth and substantial remodeling early in gestation. These changes are necessary preparations to accommodate and support rapid conceptus development and growth in the later two-thirds of pregnancy. There are species variations in the nature and extent of uterine remodeling during pregnancy. The regulatory influence of these uterine wall modifications on conceptus survival, implantation and placentation in sheep and goats are discussed in this review.
Collapse
Affiliation(s)
- U M Igwebuike
- Department of Veterinary Anatomy, University of Nigeria, Nsukka, Nigeria.
| |
Collapse
|
21
|
Uterine blood flow during the first 3 weeks of pregnancy in dairy cows. Theriogenology 2008; 70:1048-56. [DOI: 10.1016/j.theriogenology.2008.06.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2008] [Revised: 06/05/2008] [Accepted: 06/07/2008] [Indexed: 11/23/2022]
|
22
|
Wang CK, Robinson RS, Flint APF, Mann GE. Quantitative analysis of changes in endometrial gland morphology during the bovine oestrous cycle and their association with progesterone levels. Reproduction 2007; 134:365-71. [PMID: 17660245 DOI: 10.1530/rep-06-0133] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study describes a digital technique for uterine morphometry and its application to endometrial structure during the bovine oestrous cycle. Neither the number nor the size of uterine gland ducts changed during the cycle but a reduction in total endometrial area from days 0 to 8 after oestrus led to an increase in the proportion of the endometrium occupied by gland ducts (gland duct density). This effect on day 8 was maintained to day 16. When endometrial morphology was related to circulating progesterone concentrations on days 5 and 8 of the luteal phase, no relationships were found on day 5, but on day 8, a high progesterone concentration was associated with an increased number of gland ducts. Furthermore, in animals slaughtered on day 8, a high progesterone concentration on day 5 was associated with decreased gland duct size, though a simultaneous decrease in endometrial area led to an increase in gland duct density. The results suggest that contrary to expectation, endometrial glands do not grow and regress during the oestrous cycle, although cyclic changes in endometrial area controlled by progesterone lead to changes in gland duct density.
Collapse
Affiliation(s)
- C K Wang
- Division of Animal Physiology, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | | | | | | |
Collapse
|
23
|
Igwebuike UM. Trophoblast cells of ruminant placentas—A minireview. Anim Reprod Sci 2006; 93:185-98. [PMID: 16043315 DOI: 10.1016/j.anireprosci.2005.06.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 05/17/2005] [Accepted: 06/10/2005] [Indexed: 01/02/2023]
Abstract
The ruminant placenta is classified as cotyledonary and synepitheliochorial on the basis of its gross anatomical features and histological characteristics, respectively. The richly vascularized embryonic chorioallantois is lined on its external surface by cells of the trophectodermal epithelium. These cells which assume specialized functions are referred to as trophoblast cells. Two morphologically and functionally distinct cell types have been recognized in the trophectoderm of the placenta of ruminant animals. These are the mononucleate trophoblast cells and the binucleate trophoblast cells. The occurrence, morphological characteristics, and specialized functions of these trophoblast cells, in relation to conceptus nutrition and survival in utero are discussed in this review.
Collapse
Affiliation(s)
- U M Igwebuike
- Department of Veterinary Anatomy, University of Nigeria, Nsukka, Nigeria.
| |
Collapse
|
24
|
Makker A, Singh MM. Endometrial receptivity: Clinical assessment in relation to fertility, infertility, and antifertility. Med Res Rev 2006; 26:699-746. [PMID: 16710862 DOI: 10.1002/med.20061] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Fertility in humans and other mammalian species depends absolutely on synchronous events that render the developing blastocyst and the receiving uterus competent for implantation. Endometrial receptivity is defined as the period during which the endometrial epithelium acquires functional, but transient, ovarian steroid-dependent status supportive to blastocyst acceptance and implantation. Once inside the uterus, the blastocyst is surrounded by an intact luminal epithelium, which is considered to act as barrier to its attachment, except for this short period of high endometrial receptivity to blastocyst signal(s). Its transport and permeability properties, in conjunction with cellular action of the endometrium and the embryo, have been suggested to influence creation and maintenance of informational and nutritional status of uterine luminal milieu. This period, also termed as the 'window of implantation,' is limited to days 20-24 of menstrual cycle in humans. However, establishment of endometrial receptivity is still a biological mystery that remains unsolved despite marked advances in our understanding of endometrial physiology following extensive research associated with its development and function. This review deals with various structural, biochemical, and molecular events in the endometrium coordinated within the implantation window that constitute essential elements in the repertoire that signifies endometrial receptivity and is aimed to achieve a better understanding of its relationship to fertility, infertility, and for the development of targeted antifertility agents for human use and welfare.
Collapse
Affiliation(s)
- Annu Makker
- Endocrinology Division, Central Drug Research Institute, Lucknow-226 001, India
| | | |
Collapse
|
25
|
Li N, Wells DN, Peterson AJ, Lee RSF. Perturbations in the biochemical composition of fetal fluids are apparent in surviving bovine somatic cell nuclear transfer pregnancies in the first half of gestation. Biol Reprod 2005; 73:139-48. [PMID: 15788757 DOI: 10.1095/biolreprod.104.038018] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Amniotic and allantoic fluid volumes and composition change dynamically throughout gestation. Cattle that are pregnant with somatic cell nuclear transfer (NT) fetuses show a high incidence of abnormal fluid accumulation (particularly hydrallantois) and fetal mortality from approximately midgestation. To investigate fetal fluid homeostasis in these pregnancies, Na, K, Cl, urea, creatinine, Ca, Mg, total PO(4), glucose, fructose, lactate, total protein, and osmolalities were measured in amniotic and allantoic fluids collected at Days 50, 100, and 150 of gestation from NT pregnancies and those generated by the transfer of in vitro-produced embryos or by artificial insemination. Deviations in fetal fluid composition between NT and control pregnancies were apparent after placental and fetal organ development, even when no gross morphological abnormalities were observed. Individual NT fetuses were affected to varying degrees. Elevated allantoic Na was associated with lower K and increased allantoic fluid volume or edema of the fetal membranes. Total PO(4) levels in NT allantoic and amniotic fluid were elevated at Days 100 and 150. This was not accompanied by hypophosphatemia at Day 150, suggesting that PO(4) acquisition by NT fetuses was adequate but that its readsorption by the kidneys may be impaired. Excessive NT placental weight was associated with low allantoic glucose and fructose as well as high lactate levels. However, the fructogenic ability of the NT placenta appeared to be normal. The osmolality of the fetal fluids was maintained within a narrow range, suggesting that the regulation of fluid composition, but not osmolality, was impaired in NT pregnancies.
Collapse
Affiliation(s)
- Ning Li
- Reproductive Technologies Group, AgResearch, Ruakura Research Centre, Hamilton, New Zealand
| | | | | | | |
Collapse
|
26
|
Spencer TE, Johnson GA, Bazer FW, Burghardt RC. Implantation mechanisms: insights from the sheep. Reproduction 2004; 128:657-68. [PMID: 15579583 DOI: 10.1530/rep.1.00398] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Implantation in all mammals involves shedding of the zona pellucida, followed by orientation, apposition, attachment and adhesion of the blastocyst to the endometrium. Endometrial invasion does not occur in domestic ruminants; thus, definitive implantation is achieved by adhesion of the mononuclear trophoblast cells to the endometrial lumenal epithelium (LE) and formation of syncytia by the fusion of trophoblast binucleate cells with the LE. This review highlights new information on mechanisms regulating the implantation cascade in sheep. The embryo enters the uterus on day 4 at the morula stage of development and then develops into a blastocyst by day 6. The blastocyst sheds the zona pellucida (day 8), elongates to a filamentous form (days 11–16), and adheres to the endometrial LE (day 16). Between days 14 and 16, the binucleate cells begin to differentiate in the trophoblast and subsequently migrate and fuse with the endometrial LE to form syncytia. Continuous exposure of the endometrium to progesterone in early pregnancy downregulates the progesterone receptors in the epithelia, a process which is associated with loss of the cell-surface mucin MUC1 and induction of several secreted adhesion proteins. Recurrent early pregnancy loss in the uterine gland knockout ewe model indicates that secretions of the endometrial epithelia have a physiologic role in blastocyst elongation and implantation. A number of endometrial proteins have been identified as potential regulators of blastocyst development and implantation in sheep, including glycosylated cell adhesion molecule 1 (GlyCAM-1), galectin-15, integrins and osteopontin. The epithelial derived secreted adhesion proteins (GlyCAM-1, galectin-15 and osteopontin) are expressed in a dynamic temporal and spatial manner and regulated by progesterone and/or interferon tau, which is the pregnancy recognition signal produced by the trophoblast during blastocyst elongation. The noninvasive and protracted nature of implantation in domestic animals provides valuable opportunities to investigate fundamental processes of implantation that are shared among all mammals. Understanding of the cellular and molecular signals that regulate uterine receptivity and implantation can be used to diagnose and identify causes of recurrent pregnancy loss and to improve pregnancy outcome in domestic animals and humans.
Collapse
Affiliation(s)
- Thomas E Spencer
- Center for Animal Biotechnology and Genomics, Animal Science and Veterinary Anatomy and Public Health, Texas A&M University, College Station, Texas 77843, USA.
| | | | | | | |
Collapse
|
27
|
Abstract
The endometrium is the site of implantation and pregnancy. Preparation for this important biological event relies primarily on progesterone, which takes the estrogen-primed endometrium toward a state of receptivity. As a steroid target tissue, the endometrium is also prone to abnormal growth sometimes leading to the development of hyperplasia or cancer. It is the balance between estrogen and progesterone that maintains the endometrium in a state of health and provides the synchronous timing necessary for a successful implantation to occur. In our efforts to understand the role of progesterone in the endometrium we have focused on the use of specific protein biomarkers. Based on examination of a cell adhesion molecule, the alphavbeta3 integrin, and its ligand, osteopontin, we have come to conclude that progesterone action can be direct or indirect. Progesterone acting on the stromal compartment provides paracrine mediators that influence epithelial gene expression. Conversely, acting directly, progesterone may primarily stimulate gene expression of the endometrial epithelium. The complexity of the system is extended since progesterone itself works through two different receptor isoforms. Regulated differential expression of PR-A versus PR-B also appears to fine tune the effect of progesterone on specific genes. Progesterone may also inhibit specific genes that undergo cyclic variation during the menstrual cycle. Together, using in vitro models we have shown that progesterone dynamically regulates gene expression in the endometrium and that imbalances between estrogen and progesterone may have far reaching consequences on normal cycle fecundity and on the balance between health and disease in this hormone-target tissue.
Collapse
Affiliation(s)
- Bruce A Lessey
- Division of Reproductive Endocrinology and Infertility, Center for Women's Medicine, Greenville Hospital System, 890 W. Faris Road, Suite 470, Greenville, SC 29617, USA.
| |
Collapse
|
28
|
Usadi RS, Murray MJ, Bagnell RC, Fritz MA, Kowalik AI, Meyer WR, Lessey BA. Temporal and morphologic characteristics of pinopod expression across the secretory phase of the endometrial cycle in normally cycling women with proven fertility. Fertil Steril 2003; 79:970-4. [PMID: 12749439 DOI: 10.1016/s0015-0282(02)04929-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To assess the temporal and morphologic characteristics of pinopod expression on the surface of endometrium across the secretory phase, in LH-timed endometrial samples in normal, healthy women. DESIGN Prospective, randomized study. SETTING Academic teaching hospital. PATIENT(S) Sixty-eight healthy volunteers with proven fertility. INTERVENTION(S) Urinary LH-timed endometrial and blood sampling was performed on each subject on a randomly selected day of the secretory phase. MAIN OUTCOME MEASURE(S) Histologic dating, assessment of pinopods using scanning electron microscopy, and comparison with serum P levels. RESULT(S) Eighty-six endometrial tissue samples obtained from 68 subjects were evaluated under scanning electron microscopy. Pinopods were first observed on luteal day 5, corresponding with the onset of the midluteal phase increase in serum P levels. Pinopods persisted for the entire duration of the secretory phase, but their morphology changed as the cycle advanced. CONCLUSION(S) The present findings demonstrate that pinopods are a characteristic feature of the mid to late secretory phase endometrial epithelium, exhibit cycle-dependent changes in morphology, and are most prominent during the putative implantation interval.
Collapse
Affiliation(s)
- Rebecca S Usadi
- University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina, USA
| | | | | | | | | | | | | |
Collapse
|
29
|
Murphy CR. Understanding the apical surface markers of uterine receptivity: pinopods-or uterodomes? Hum Reprod 2000; 15:2451-4. [PMID: 11098008 DOI: 10.1093/humrep/15.12.2451] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The plasma membrane of uterine epithelial cells is very sensitive to ovarian hormones and protrusions of the apical portion of this membrane have been used as indicators of endocrine status and preparation for implantation in the human uterus in particular. Protrusions of the apical plasma membrane were first identified in rats and mice where their established pinocytotic function gave rise to the name 'pinopod'. In humans and many other animals however, little evidence of the functional nature of such protrusions is available but what is available suggests that human 'pinopods' (useful though they are as indicators of endocrine status) might be more similar morphologically to other, larger, membrane protrusions, or apical domes, which have been shown not to be pinocytotic. Hence, I propose that these latter protrusions, including those in the human uterus, should be referred to by a term which does not imply a particular function and have settled on the name 'uterodome'.
Collapse
Affiliation(s)
- C R Murphy
- Department of Anatomy and Histology, F13, The University of Sydney, NSW 2006, Australia.
| |
Collapse
|
30
|
Emond V, Asselin E, Fortier MA, Murphy BD, Lambert RD. Interferon-tau stimulates granulocyte-macrophage colony-stimulating factor gene expression in bovine lymphocytes and endometrial stromal cells. Biol Reprod 2000; 62:1728-37. [PMID: 10819777 DOI: 10.1095/biolreprod62.6.1728] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Interferon-tau (IFN-tau), the antiluteolytic signal produced by the trophoblast prior to implantation in ruminants, exhibits immunomodulatory properties. It stimulates the production of prostaglandin (PG) E(2) in bovine endometrial cells via the induction of cyclooxygenase-2 (COX-2). We previously demonstrated that preconditioning lymphocytes with PGE(2) increases the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that promotes conceptus growth and survival. Our goal in the present study was to evaluate the impact of IFN-tau on the expression of GM-CSF in bovine peripheral blood lymphocytes (PBL) and endometrial epithelial and stromal cells. Changes in PGE(2) production and mRNA levels of COX-2 were also studied in PBL in response to IFN-tau. Gene expression was estimated by semiquantitative reverse transcription-polymerase chain reaction and Northern analysis. The expression of GM-CSF in PBL was stimulated by treatment with IFN-tau. Furthermore, GM-CSF mRNA levels were increased after preconditioning PBL for 3 days with IFN-tau, followed by a 12-h restimulation without IFN-tau. Inhibition rather than stimulation of PGE(2) production and COX-2 expression in PBL during treatment with IFN-tau suggests a direct effect on GM-CSF expression. Moreover, GM-CSF expression was stimulated in uterine stromal cells in response to IFN-tau. This study provides the first evidence for stimulation of GM-CSF expression by IFN-tau in both leukocytes and endometrial stromal cells. In view of the role of GM-CSF on fetal growth and survival, these results support the hypothesis that the conceptus mediates accommodation mechanisms in the uterus during early pregnancy by modulating the expression of beneficial cytokines at the fetomaternal interface.
Collapse
Affiliation(s)
- V Emond
- Unité de Recherche en Ontogénie et Reproduction, Centre de Recherche du Centre Hospitalier de l'Université Laval, Ste-Foy, Québec, Canada G1V 4G2
| | | | | | | | | |
Collapse
|
31
|
Peiris ID, Grewal TS, Jeacock MK, Savva D, Shepherd DA. Effect of a novel recombinant bovine interferon and trophoblast secretory products on protein metabolism by endometrial explants from cattle and sheep. Res Vet Sci 1998; 64:79-83. [PMID: 9557811 DOI: 10.1016/s0034-5288(98)90120-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The effect of a novel recombinant bovine interferon on the rate of protein synthesis, as measured by the rate of leucine incorporation, in endometrial explants from cows and ewes was investigated and compared with the effect of trophoblast secretory proteins and of a recombinant bovine interferon-alpha1. Exposure of cultured bovine endometrial tissue to the novel recombinant bovine interferon mimicked the effect of pregnancy in reducing the rate of protein synthesis in both caruncular and intercaruncular endometrium. This effect was similar to that seen with naturally produced trophoblast secretory proteins and it was more pronounced than that seen when endometrial tissue was treated with a related recombinant bovine interferon-alpha1. Ovine endometrial cultures were unaffected by exposure to this novel recombinant bovine interferon. This novel recombinant interferon exhibited potent antiviral properties (an activity of 1.6 x 10(10) international reference units/mg protein) and may prove to be a valuable reagent in studying the maternal recognition of pregnancy in the cow and reducing embryo mortality.
Collapse
Affiliation(s)
- I D Peiris
- School of Animal and Microbial Sciences, The University of Reading, Whiteknights
| | | | | | | | | |
Collapse
|
32
|
Ruéda BR, Naivar KA, George EM, Austin KJ, Francis H, Hansen TR. Recombinant interferon-tau regulates secretion of two bovine endometrial proteins. JOURNAL OF INTERFERON RESEARCH 1993; 13:303-9. [PMID: 8228390 DOI: 10.1089/jir.1993.13.303] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Conceptus-derived interferon-tau (IFN-tau) has been implicated in the process of maternal recognition of pregnancy in the bovine. This type I IFN interacts with a uterine receptor complex to elicit secondary maternal responses, one of which is secretion of uterine proteins. We investigated the effects of pregnancy and recombinant (r) bovine (bo) IFN-tau (10(7) antiviral units/mg) on secreted proteins by cultured bovine endometrial explants. Explants were cultured for 24 h with [3H]leucine and dialyzed medium analyzed by one- and two-dimensional SDS polyacrylamide gel electrophoresis (PAGE) and fluorography. In one-dimensional PAGE experiments, endometrium representing early pregnancy (days 16-21) and the estrous cycle (days 16-19) was cultured in the presence of 5 nM rboIFN-tau and showed an increase (two- to five-fold) in secretion of 12- and 28-kD proteins. Further examination of these proteins by using two-dimensional PAGE indicated that the 12-kD protein was basic (pI > or = 7.5), whereas the 28-kD protein was acidic (pI approximately 5.0). Isoelectric focusing in the acidic range revealed that the 28-kD protein was composed of several isoelectric variants (pI 4.5-5.5). Although the functions of these secretory proteins are currently unknown, they serve as useful markers for IFN action and may act as secondary signals to protect the early developing conceptus.
Collapse
Affiliation(s)
- B R Ruéda
- Department of Animal Science, University of Wyoming, Laramie 82071
| | | | | | | | | | | |
Collapse
|
33
|
Dantzer V. INITIAL PLACENTATION IN FARM ANIMALS MORPHOLOGICAL EVENTS WHERE GROWTH FACTORS MUST BE IMPLICATED. Reprod Domest Anim 1993. [DOI: 10.1111/j.1439-0531.1993.tb00122.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
34
|
Wrobel KH, Kujat R, Fehle G. The bovine tubouterine junction: general organization and surface morphology. Cell Tissue Res 1993; 271:227-39. [PMID: 8453653 DOI: 10.1007/bf00318609] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The bovine tubouterine junction is composed of three parts (terminal tubal segment, transition region proper, uterine apex) and follows a sigmoidal course displaying a tubal and an uterine curvature. In the terminal tubal segment, 4-8 primary longitudinal folds and a system of lower secondary folds, ridges and chords project into the centrally located lumen. The transition region proper possesses a slit-like lumen because of the existence of a thick mucosal pad containing the first uterine glands. The longitudinal primary folds of the tube broaden, flatten and start to diverge when they reach the transition region proper. The mucosal pad and broadened folds are heavily vascularized. A system of lateral outpocketings with blind ends pointing in an ampullary direction develops between the primary and secondary folds, the ridges and chords of the terminal tubal segment and transition region proper. From the bottom of these outpocketings, short tubulo-alveolar crypts originate. The mucosa of the uterine apex forms low transversal ridges. The musculature of the bovine tubouterine junction is divided into a continuous circular or spiral intermediate layer, flanked by inner and outer longitudinal layers. The outer longitudinal layer is incomplete in the terminal tubal segment but increases in thickness to form a continuous stratum in the uterine apex. An inner longitudinal layer occurs only in the terminal tubal segment where it is best developed in the bases of the primary longitudinal folds. The simple columnar surface epithelium of the tubouterine junction contains ciliated and non-ciliated cells. The former undergo cyclical changes, and increase during estrus and postestrus. During proestrus, groups of non-ciliated cells display bulbous apical protrusions. During proestrus and estrus, circumscribed epithelial lesions expose the underlying basal lamina.
Collapse
Affiliation(s)
- K H Wrobel
- Institut für Anatomie der Universität, Regensburg, Federal Republic of Germany
| | | | | |
Collapse
|
35
|
Murphy CR. The plasma membrane of uterine epithelial cells: structure and histochemistry. PROGRESS IN HISTOCHEMISTRY AND CYTOCHEMISTRY 1993; 27:1-66. [PMID: 8265798 DOI: 10.1016/s0079-6336(11)80004-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- C R Murphy
- Department of Histology and Embryology, University of Sydney, New South Wales, Australia
| |
Collapse
|
36
|
The Development of the Conceptus and Its Relationship to the Uterus. Reprod Domest Anim 1991. [DOI: 10.1016/b978-0-08-057109-6.50014-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
37
|
Keys JL, King GJ. Microscopic examination of porcine conceptus-maternal interface between days 10 and 19 of pregnancy. THE AMERICAN JOURNAL OF ANATOMY 1990; 188:221-38. [PMID: 2371964 DOI: 10.1002/aja.1001880302] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Conceptus-maternal interactions in the pig were examined at days 10, 13, 16, and 19 of pregnancy. Contact between the chorion and uterine epithelium was not preserved on day 10, but extensive contact occurred in 3 of 5 pregnant gilts on day 13 and was related to localized differentiation of the uterine epithelium. Attachment events occurred earlier and more rapidly than previously reported, commencing in the region of the embryonic disc and progressing toward the extremities of the chorionic vesicle, with stages from apposition through attachment occurring simultaneously along a conceptus at day 13 and thereafter. Apical protuberances on maternal epithelial cells and interposing blunt chorionic processes were evident at sites of early maternal-conceptus interaction, but were reduced at regions exhibiting microvillous interdigitation. Placentation in the pig represents a developmental process consisting of a continuum of sequential events which occur over a broad time frame rather than at specific discrete times.
Collapse
Affiliation(s)
- J L Keys
- Department of Animal and Poultry Science, University of Guelph, Ontario, Canada
| | | |
Collapse
|
38
|
|
39
|
Gustafsson H, Plöen L. The morphology of 16 and 17 day old bovine blastocysts from virgin and repeat breeder heifers. Anat Histol Embryol 1986; 15:277-87. [PMID: 2947524 DOI: 10.1111/j.1439-0264.1986.tb00719.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
40
|
Dantzer V. Electron microscopy of the initial stages of placentation in the pig. ANATOMY AND EMBRYOLOGY 1985; 172:281-93. [PMID: 4061869 DOI: 10.1007/bf00318976] [Citation(s) in RCA: 145] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
To elucidate the morphology of the initial stages of epitheliochorial placentation in the pig, material from 10 sows of the Danish Landrace and from one Göttinger minipig gilt from day 13 to day 26 of gestation was processed for scanning and transmission electron microscopy. The observed foetomaternal interaction from day 19 1/2 minipig placenta corresponded well to the observations on the Danish Landrace placenta. From the results and the discussion it was concluded that the following structures were implicated in the initial phases of placentation in the pig: Protruding epithelial proliferations of the uterine epithelium enclosed by chorionic caps serving to immobilize the blastocyst (days 13 and 14). A thick glycocalyx on the maternal and a thin one on the foetal epithelium before contact. Close apposition between the apical plasma membranes from trophoblastic and uterine epithelium (day 14). Development of interdigitating microvilli (days 15-16). Formation of apical domes on the uterine epithelium closely related to the trophoblast provided with long cytoplasmic extensions into a luminal space between the apical domes, apparently representing a transition from histiotropic to haemotrophic nutrition (days 15-20). Placentation, development of interdigitating microvilli between foetal and maternal epithelium, was extended but not terminated in the peripheral zone at day 26.
Collapse
|