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Pfeffer PL. Alternative mammalian strategies leading towards gastrulation: losing polar trophoblast (Rauber's layer) or gaining an epiblast cavity. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210254. [PMID: 36252216 PMCID: PMC9574635 DOI: 10.1098/rstb.2021.0254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Using embryological data from 14 mammalian orders, the hypothesis is presented that in placental mammals, epiblast cavitation and polar trophoblast loss are alternative developmental solutions to shield the central epiblast from extraembryonic signalling. It is argued that such reciprocal signalling between the edge of the epiblast and the adjoining polar trophoblast or edge of the mural trophoblast or with the amniotic ectoderm is necessary for the induction of gastrulation. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
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Affiliation(s)
- Peter L. Pfeffer
- School of Biological Sciences, Victoria University of Wellington, Kelburn Parade, Wellington 6010, New Zealand
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2
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Derisoud E, Jouneau L, Dubois C, Archilla C, Jaszczyszyn Y, Legendre R, Daniel N, Peynot N, Dahirel M, Auclair-Ronzaud J, Wimel L, Duranthon V, Chavatte-Palmer P. Maternal age affects equine day 8 embryo gene expression both in trophoblast and inner cell mass. BMC Genomics 2022; 23:443. [PMID: 35705916 PMCID: PMC9199136 DOI: 10.1186/s12864-022-08593-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/22/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Breeding a mare until she is not fertile or even until her death is common in equine industry but the fertility decreases as the mare age increases. Embryo loss due to reduced embryo quality is partly accountable for this observation. Here, the effect of mare's age on blastocysts' gene expression was explored. Day 8 post-ovulation embryos were collected from multiparous young (YM, 6-year-old, N = 5) and older (OM, > 10-year-old, N = 6) non-nursing Saddlebred mares, inseminated with the semen of one stallion. Pure or inner cell mass (ICM) enriched trophoblast, obtained by embryo bisection, were RNA sequenced. Deconvolution algorithm was used to discriminate gene expression in the ICM from that in the trophoblast. Differential expression was analyzed with embryo sex and diameter as cofactors. Functional annotation and classification of differentially expressed genes and gene set enrichment analysis were also performed. RESULTS Maternal aging did not affect embryo recovery rate, embryo diameter nor total RNA quantity. In both compartments, the expression of genes involved in mitochondria and protein metabolism were disturbed by maternal age, although more genes were affected in the ICM. Mitosis, signaling and adhesion pathways and embryo development were decreased in the ICM of embryos from old mares. In trophoblast, ion movement pathways were affected. CONCLUSIONS This is the first study showing that maternal age affects gene expression in the equine blastocyst, demonstrating significant effects as early as 10 years of age. These perturbations may affect further embryo development and contribute to decreased fertility due to aging.
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Affiliation(s)
- Emilie Derisoud
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France.
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France.
| | - Luc Jouneau
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Cédric Dubois
- IFCE, Plateau technique de Chamberet, 19370, Chamberet, France
| | - Catherine Archilla
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Yan Jaszczyszyn
- Institute for Integrative Biology of the Cell (I2BC), UMR 9198 CNRS, CEA, Paris-Sud University F-91198, Gif-sur-Yvette, France
| | - Rachel Legendre
- Institut Pasteur-Bioinformatics and Biostatistics Hub-Department of Computational Biology, Paris, France
| | - Nathalie Daniel
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Nathalie Peynot
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Michèle Dahirel
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | | | - Laurence Wimel
- IFCE, Plateau technique de Chamberet, 19370, Chamberet, France
| | - Véronique Duranthon
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Pascale Chavatte-Palmer
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France.
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France.
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Harmoush B, Tsikolia N, Viebahn C. Epiblast and trophoblast morphogenesis in the pre-gastrulation blastocyst of the pig. A light- and electron-microscopical study. J Morphol 2021; 282:1339-1361. [PMID: 34176156 DOI: 10.1002/jmor.21389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 05/31/2021] [Accepted: 06/15/2021] [Indexed: 01/18/2023]
Abstract
The epiblast of the amniote embryo is of paramount importance during early development as it gives rise to all tissues of the embryo proper. In mammals, it emerges through segregation of the hypoblast from the inner cell mass and subsequently undergoes transformation into an epithelial sheet to create the embryonic disc. In rodents and man, the epiblast cell layer is covered by the polar trophoblast which forms the placenta. In mammalian model organisms (rabbit, pig, several non-human primates), however, the placenta is formed by mural trophoblast whereas the polar trophoblast disintegrates prior to gastrulation and thus exposes the epiblast to the microenvironment of the uterine cavity. Both, polar trophoblast disintegration and epiblast epithelialization, thus pose special cell-biological requirements but these are still rather ill-understood when compared to those of gastrulation morphogenesis. This study therefore applied high-resolution light and transmission electron microscopy and three-dimensional (3D) reconstruction to 8- to 10-days-old pig embryos and defines the following steps of epiblast transformation: (1) rosette formation in the center of the ball-shaped epiblast, (2) extracellular cavity formation in the rosette center, (3) epiblast segregation into two subpopulations - addressed here as dorsal and ventral epiblast - separated by a "pro-amniotic" cavity. Ventral epiblast cells form between them a special type of desmosomes with a characteristic dense felt of microfilaments and are destined to generate the definitive epiblast. The dorsal epiblast remains a mass of non-polarized cells and closely associates with the disintegrating polar trophoblast, which shows morphological features of both apoptosis and autophagocytosis. Morphogenesis of the definitive epiblast in the pig may thus exclude a large portion of bona fide epiblast cells from contributing to the embryo proper and establishes contact de novo with the mural trophoblast at the junction between the two newly defined epiblast cell populations.
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Affiliation(s)
- Braah Harmoush
- Institute of Anatomy and Embryology, University Medical Centre Göttingen, Göttingen, Germany
| | - Nikoloz Tsikolia
- Institute of Anatomy and Embryology, University Medical Centre Göttingen, Göttingen, Germany
| | - Christoph Viebahn
- Institute of Anatomy and Embryology, University Medical Centre Göttingen, Göttingen, Germany
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Pérez-Gómez A, González-Brusi L, Bermejo-Álvarez P, Ramos-Ibeas P. Lineage Differentiation Markers as a Proxy for Embryo Viability in Farm Ungulates. Front Vet Sci 2021; 8:680539. [PMID: 34212020 PMCID: PMC8239129 DOI: 10.3389/fvets.2021.680539] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 05/24/2021] [Indexed: 12/28/2022] Open
Abstract
Embryonic losses constitute a major burden for reproductive efficiency of farm animals. Pregnancy losses in ungulate species, which include cattle, pigs, sheep and goats, majorly occur during the second week of gestation, when the embryo experiences a series of cell differentiation, proliferation, and migration processes encompassed under the term conceptus elongation. Conceptus elongation takes place following blastocyst hatching and involves a massive proliferation of the extraembryonic membranes trophoblast and hypoblast, and the formation of flat embryonic disc derived from the epiblast, which ultimately gastrulates generating the three germ layers. This process occurs prior to implantation and it is exclusive from ungulates, as embryos from other mammalian species such as rodents or humans implant right after hatching. The critical differences in embryo development between ungulates and mice, the most studied mammalian model, have precluded the identification of the genes governing lineage differentiation in livestock species. Furthermore, conceptus elongation has not been recapitulated in vitro, hindering the study of these cellular events. Luckily, recent advances on transcriptomics, genome modification and post-hatching in vitro culture are shedding light into this largely unknown developmental window, uncovering possible molecular markers to determine embryo quality. In this review, we summarize the events occurring during ungulate pre-implantation development, highlighting recent findings which reveal that several dogmas in Developmental Biology established by knock-out murine models do not hold true for other mammals, including humans and farm animals. The developmental failures associated to in vitro produced embryos in farm animals are also discussed together with Developmental Biology tools to assess embryo quality, including molecular markers to assess proper lineage commitment and a post-hatching in vitro culture system able to directly determine developmental potential circumventing the need of experimental animals.
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Affiliation(s)
- Alba Pérez-Gómez
- Department of Animal Reproduction, National Institute for Agriculture and Food Research and Technology (INIA), Madrid, Spain
| | - Leopoldo González-Brusi
- Department of Animal Reproduction, National Institute for Agriculture and Food Research and Technology (INIA), Madrid, Spain
| | - Pablo Bermejo-Álvarez
- Department of Animal Reproduction, National Institute for Agriculture and Food Research and Technology (INIA), Madrid, Spain
| | - Priscila Ramos-Ibeas
- Department of Animal Reproduction, National Institute for Agriculture and Food Research and Technology (INIA), Madrid, Spain
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5
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Abstract
The polar trophoblast overlays the epiblast in eutherian mammals and, depending on the species, has one of two different fates. It either remains a single-layered, thinning epithelium called "Rauber's layer," which soon disintegrates, or, alternatively, it keeps proliferating, contributing heavily to the population of differentiating, invasive trophoblast cells and, at least in mice, to the induction of gastrulation. While loss of the persistent polar trophoblast in mice leads to reduced induction of gastrulation, we show here that prevention of the loss of the polar trophoblast in cattle results in ectopic domains of the gastrulation marker, BRACHYURY This phenotype, and increased epiblast proliferation, arose when Rauber's layer was maintained for a day longer by countering apoptosis through BCL2 overexpression. This suggests that the disappearance of Rauber's layer is a necessity, presumably to avoid excessive signaling interactions between this layer and the subjacent epiblast. We note that, in all species in which the polar trophoblast persists, including humans and mice, ectopic polar trophoblast signaling is prevented via epiblast cavitation which leads to the (pro)amniotic cavity, whose function is to distance the central epiblast from such signaling interactions.
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6
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Carter AM. The role of mammalian foetal membranes in early embryogenesis: Lessons from marsupials. J Morphol 2020; 282:940-952. [PMID: 32374455 DOI: 10.1002/jmor.21140] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/20/2020] [Accepted: 04/25/2020] [Indexed: 12/16/2022]
Abstract
Across mammals, early embryonic development is supported by uterine secretions taken up through the yolk sac and other foetal membranes (histotrophic nutrition). The marsupial conceptus is enclosed in a shell coat for the first two-thirds of gestation and nutrients pass to the embryo through the shell and the avascular bilaminar yolk sac. At around the time of shell rupture, part of the yolk sac is trilaminar and supplied with blood vessels. It attaches to the uterus and forms a choriovitelline placenta. Rapid growth of the embryo ensues, still supported by histotrophe as well as exchange of oxygen and nutrients between maternal and foetal blood vessels (haemotrophic nutrition). Few marsupials have a chorioallantoic placenta and the highly altricial newborn is delivered after a short gestation. Eutherian embryos pass through a similar sequence before there is a fully functional chorioallantoic placenta. In most orders, there is transient yolk sac placentation, but even before this, nutrients are transferred through an avascular yolk sac. Yolk sac placentation does not occur in rodents or catarrhine primates. Early embryonic development in the mouse is nonetheless dependent on histotrophic nutrition. In the first trimester of human pregnancy, uterine glands open to the intervillous space and secretion products are taken up by the trophoblast. Transfer of nutrients to the early human embryo also involves the yolk sac, which floats free in the exocoelom. Marsupials can therefore inform us about the role of foetal membranes and histotrophic nutrition in early embryogenesis, knowledge that can translate to eutherians.
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Affiliation(s)
- Anthony M Carter
- Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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7
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Favaron PO, Carvalho RC, Borghesi J, Anunciação ARA, Miglino MA. The Amniotic Membrane: Development and Potential Applications - A Review. Reprod Domest Anim 2015; 50:881-92. [DOI: 10.1111/rda.12633] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 09/23/2015] [Indexed: 02/06/2023]
Affiliation(s)
- PO Favaron
- Department of Surgery; School of Veterinary Medicine and Animal Science; University of Sao Paulo; São Paulo São Paulo Brazil
| | - RC Carvalho
- Center of Agricultural and Environmental Sciences; Federal University of Maranhão; Boa Vista Chapadinha Maranhão Brazil
| | - J Borghesi
- Department of Surgery; School of Veterinary Medicine and Animal Science; University of Sao Paulo; São Paulo São Paulo Brazil
| | - ARA Anunciação
- Department of Surgery; School of Veterinary Medicine and Animal Science; University of Sao Paulo; São Paulo São Paulo Brazil
| | - MA Miglino
- Department of Surgery; School of Veterinary Medicine and Animal Science; University of Sao Paulo; São Paulo São Paulo Brazil
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Gaivão MMF, Rambags BPB, Stout TAE. Gastrulation and the establishment of the three germ layers in the early horse conceptus. Theriogenology 2014; 82:354-65. [PMID: 24857628 DOI: 10.1016/j.theriogenology.2014.04.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 11/16/2022]
Abstract
Experimental studies and field surveys suggest that embryonic loss during the first 6 weeks of gestation is a common occurrence in the mare. During the first 2 weeks of development, a number of important cell differentiation events must occur to yield a viable embryo proper containing all three major germ layers (ectoderm, mesoderm, and endoderm). Because formation of the mesoderm and primitive streak are critical to the development of the embryo proper, but have not been described extensively in the horse, we examined tissue development and differentiation in early horse conceptuses using a combination of stereomicroscopy, light microscopy, and immunohistochemistry. Ingression of epiblast cells to form the mesoderm was first observed on day 12 after ovulation; by Day 18 the conceptus had completed a series of differentiation events and morphologic changes that yielded an embryo proper with a functional circulation. While mesoderm precursor cells were present from Day 12 after ovulation, vimentin expression was not detectable until Day 14, suggesting that initial differentiation of mesoderm from the epiblast in the horse is independent of this intermediate filament protein, a situation that contrasts with other domestic species. Development of the other major embryonic germ layers was similar to other species. For example, ectodermal cells expressed cytokeratins, and there was a clear demarcation in staining intensity between embryonic ectoderm and trophectoderm. Hypoblast showed clear α1-fetoprotein expression from as early as Day 10 after ovulation, and seemed to be the only source of α1-fetoprotein in the early conceptus.
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Affiliation(s)
- Maria M F Gaivão
- Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
| | - Björn P B Rambags
- Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Tom A E Stout
- Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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9
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Nowak-Imialek M, Niemann H. Pluripotent cells in farm animals: state of the art and future perspectives. Reprod Fertil Dev 2013; 25:103-28. [PMID: 23244833 DOI: 10.1071/rd12265] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Pluripotent cells, such as embryonic stem (ES) cells, embryonic germ cells and embryonic carcinoma cells are a unique type of cell because they remain undifferentiated indefinitely in in vitro culture, show self-renewal and possess the ability to differentiate into derivatives of the three germ layers. These capabilities make them a unique in vitro model for studying development, differentiation and for targeted modification of the genome. True pluripotent ESCs have only been described in the laboratory mouse and rat. However, rodent physiology and anatomy differ substantially from that of humans, detracting from the value of the rodent model for studies of human diseases and the development of cellular therapies in regenerative medicine. Recently, progress in the isolation of pluripotent cells in farm animals has been made and new technologies for reprogramming of somatic cells into a pluripotent state have been developed. Prior to clinical application of therapeutic cells differentiated from pluripotent stem cells in human patients, their survival and the absence of tumourigenic potential must be assessed in suitable preclinical large animal models. The establishment of pluripotent cell lines in farm animals may provide new opportunities for the production of transgenic animals, would facilitate development and validation of large animal models for evaluating ESC-based therapies and would thus contribute to the improvement of human and animal health. This review summarises the recent progress in the derivation of pluripotent and reprogrammed cells from farm animals. We refer to our recent review on this area, to which this article is complementary.
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Affiliation(s)
- Monika Nowak-Imialek
- Institut of Farm Animal Genetics, Friedrich-Loefller-Institut (FLI), Biotechnology, Höltystrasse 10, Mariensee, 31535 Neustadt, Germany.
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10
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ENDERS AC, SCHLAFKE S, LANTZ KC, LIU IKM. Endoderm cells of the equine yolk sac from Day 7 until formation of the definitive yolk sac placenta. Equine Vet J 2010. [DOI: 10.1111/j.2042-3306.1993.tb04814.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Walter I, Tschulenk W, Budik S, Aurich C. Transmission electron microscopy (TEM) of equine conceptuses at 14 and 16 days of gestation. Reprod Fertil Dev 2010; 22:405-15. [PMID: 20047726 DOI: 10.1071/rd08280] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 07/27/2009] [Indexed: 11/23/2022] Open
Abstract
The present study gives a detailed ultrastructural description of equine conceptuses at Day 14 (n = 2) and Day 16 (n = 3) after ovulation. Whereas on Day 14 only primitive structures were seen, on Day 16 neurulation and formation of mesodermal somites had taken place. The ectoderm of the embryo itself and the surrounding trophoblast ectodermal cells were characterised by specific cell surface differentiations. At the embryonic ectodermal cell surface (14 and 16 days) remarkable protruded and fused cytoplasmic projections were seen, typically associated with macropinocytotic events involved in macromolecule and fluid uptake. This finding adds an important point to the expansion mode of the hypotone equine conceptus, which is characterised by 'uphill' fluid uptake. Numerous microvilli and coated endocytotic pits at the apical trophoblast membrane emphasised its absorptive character. Endodermal cells were arranged loosely with only apically located cellular junctions leaving large intercellular compartments. At the border of the embryonic disc apoptotic cells were regularly observed indicating high remodelling activities in this area. Conspicuous blister-like structures between ectoderm and mesoderm were seen in the trilaminar part of Day-14 and -16 conceptuses. These were strictly circumscribed despite not being sealed by cellular junctions between germinal layers. It is possible that these blisters are involved in embryo positioning; however, further studies are needed to verify this.
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Affiliation(s)
- Ingrid Walter
- Institute of Histology and Embryology, Department of Pathobiology, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria.
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Crews LJ, Waelchli RO, Huang CX, Canny MJ, McCully ME, Betteridge KJ. Electrolyte distribution and yolk sac morphology in frozen hydrated equine conceptuses during the second week of pregnancy. Reprod Fertil Dev 2007; 19:804-14. [PMID: 17897583 DOI: 10.1071/rd07050] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Accepted: 05/21/2007] [Indexed: 11/23/2022] Open
Abstract
To investigate how equine conceptuses expand rapidly despite the hypo-osmolality of their yolk sac fluid, 18 conceptuses, aged 8–12 days and 0.8–10.0 mm in diameter, were examined by cryoscanning electron microscopy and energy dispersive X-ray microanalysis to determine the distribution of Na, Cl and K in their fluids. No osmotic gradient was found between central and peripheral yolk sac fluid. In conceptuses ≥ 6 mm in diameter, the concentrations of both Na and K in the subtrophectodermal compartments were higher than those determined previously in uterine fluid, supporting the concept of osmotic intake of fluid from the uterine environment as far as the compartments. However, electrolyte concentrations in the compartments consistently exceeded those found in the yolk sac, making it likely that ‘uphill’ water transport, rather than a purely osmotic uptake, is involved in yolk sac fluid accumulation. We also speculate that capsule formation could actively contribute to conceptus expansion and thereby to fluid intake.
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Affiliation(s)
- Laura J Crews
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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14
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Abstract
The developmental changes in the equine conceptus, its maternal environment and their interaction during the first 4 weeks following fertilization are reviewed. Attention is drawn to species-specific events to show why the horse is such a valuable model in which to study early pregnancy.
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Affiliation(s)
- K J Betteridge
- Animal Biotechnology-Embryo Laboratory, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Ontario, Guelph, Canada
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15
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Crossett B, Suire S, Herrler A, Allen WR, Stewart F. Transfer of a uterine lipocalin from the endometrium of the mare to the developing equine conceptus. Biol Reprod 1998; 59:483-90. [PMID: 9716544 DOI: 10.1095/biolreprod59.3.483] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
One of the major, progesterone-dependent proteins secreted into the uterine lumen of the mare is a 19-kDa lipocalin (P19). It associates strongly with the embryonic capsule that envelops the young horse conceptus in early gestation, suggesting that it may be involved in sustaining early development. However, it was not known whether the protein was transported through the capsule and/or trophoblast layer and into the yolk sac cavity. To address this question, polyclonal antisera were raised against a C-terminal peptide (based on the deduced amino acid sequence of P19) and a recombinant-derived P19 fusion protein. The antiserum raised against the C-terminal peptide recognized P19 on Western blots of denatured uterine secretions (subjected to SDS-PAGE), but it did not bind to the protein in tissue sections. However, the antiserum raised against the recombinant-derived fusion protein recognized P19 both on Western blots and in histological sections. Western blot analysis of tissues and fluids collected from early-pregnant mares demonstrated significant quantities of P19 in the endometrium and uterine secretions and in the embryonic capsule, the chorion, and the yolk sac fluid, showing that the protein is transferred through to the developing embryo. Concentrations of immunoreactive P19 declined during gestation so that, by Day 30, it had virtually disappeared from both maternal and fetal tissues and fluids. Immunohistochemical staining of endometrial biopsies collected during early pregnancy localized P19 to the glandular and luminal epithelia and to the lumina of the endometrial glands. The capsule and the trophoblast layer of the chorion from early (Days 16-17) horse conceptuses also stained positively with localization of P19 to the apical surface of the trophoblast cells. There was no detectable staining either in or on the embryonic disc. The presence of P19 in both the trophoblast layer and the yolk sac fluid suggests that P19 passes into the yolk sac fluid via trophoblast cells.
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Affiliation(s)
- B Crossett
- University of Cambridge, Department of Clinical Veterinary Medicine, Equine Fertility Unit, Mertoun Paddocks, Newmarket, CB8 9BH, United Kingdom
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17
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Cruz YP. Role of ultrastructural studies in the analysis of cell lineage in the mammalian pre-implantation embryo. Microsc Res Tech 1992; 22:103-25. [PMID: 1617205 DOI: 10.1002/jemt.1070220108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ultrastructural studies have contributed significantly to our understanding of cell lineage differentiation in the mammalian pre-implantation embryo. Such studies have documented, and continue to document, morphological, biochemical, and physiological characteristics of the cell lineages established during the pre-implantation period in eutherian embryos, principally that of the mouse. This review evaluates these contributions and identifies areas of study in which ultrastructural analysis is most likely to have an important role in the future.
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Affiliation(s)
- Y P Cruz
- Department of Biology, Oberlin College, Ohio 44074
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Watson ED, Zanecosky HG. Regulation of mitogen- and TCGF-induced lymphocyte blastogenesis by prostaglandins and supernatant from equine embryos and endometrium. Res Vet Sci 1991; 51:61-5. [PMID: 1896632 DOI: 10.1016/0034-5288(91)90032-j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Immunosuppressive substances which interfere with lymphocyte blastogenesis are released in vitro by embryos and endometrium from mares in early pregnancy. Immunosuppression was not evident when tissues were cultured in the presence of indomethacin (a prostaglandin-synthesis inhibitor). Various prostaglandins (PGs) were added to equine lymphocytes and lymphocyte proliferation was measured after the addition of concanavalin A (Con A) or phytohaemagglutinin A (PHA). PGE2 and PGF2 alpha inhibited Con A-induced blastogenesis down to final concentrations of 1.8 x 10(-9) M and 1.3 x 10(-6) M, respectively. Other PGs tested (6-keto-PGF1 alpha and 13,14-dihydro-15-keto-PGF2 alpha) did not affect Con A-induced blastogenesis. PHA-induced blastogenesis was inhibited by concentrations down to 1.8 x 10(-9) M PGE2, 3.3 x 10(-7) M PGF2 alpha and 2.8 x 10(-4) M 6-keto-PGF1 alpha. At all concentrations, 13,14-dihydro-15-keto-PGF2 alpha only slightly reduced PHA-induced blastogenesis. Therefore, PGE2 was the only prostaglandin tested which, at physiological concentrations, significantly inhibited incorporation of [3H] thymidine. The mechanism of PGE2-mediated suppression was studied by adding PGE2 and T cell growth factors (TCGF) to TCGF-responsive lymphocytes. PGE2 reduced the TCGF-mediated blastogenic response in a dose-dependent manner. Furthermore, culture supernatant from embryos and endometrium from 14-day pregnant mares inhibited lymphocyte blastogenesis induced by TCGF. These results show that PGE2 interferes with lymphocyte blastogenesis by TCGF-dependent mechanisms. It is suggested that the PGE2 present in the uterus of the early pregnant mare may be one of the factors involved in immunosuppression at the time of maternal recognition of pregnancy.
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Affiliation(s)
- E D Watson
- Section of Reproductive Studies, University of Pennsylvania, New Bolton Center, School of Veterinary Medicine, Kennett Square 19348
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Abstract
The germinal area of the rabbit blastocyst between 108 h postcoitum (pc) and 168 h pc has been examined by scanning electron and transmission electron microscopy. At 108 h and 120 h pc the polar trophoblast (Rauber's layer) is an intact epithelium overlying the epiblast of the inner cell mass. By 132 h pc the polar trophoblast cells begin to separate at multiple foci, exposing the underlying epiblast. Most of the polar trophoblast cells have become individually separated at 144 h pc. The villous, electron-dense polar trophoblast cells can be easily distinguished from the cells of the epiblast, which have smooth apical surfaces. By 162 h pc the polar trophoblast cells have disappeared from the germinal area. Before the polar trophoblast breaks up, the underlying epiblast cells are only loosely attached to one another. Concurrent with the disintegration of the trophoblast epithelium, the epiblast cells change in shape so that their lateral borders become closely apposed, and junctions develop to form a new epithelium. The epiblast becomes contiguous with the mural trophoblast, and thus the blastocyst does not lose its turgidity as the permeability seal is maintained. There are two classical theories on the fate of the polar trophoblast: the cells die, or they become incorporated into the epiblast as living cells. In newly exposed epiblast the presence of very large phagosomes, which are not found when the polar trophoblast is still intact, favors the first hypothesis and indicates that in the rabbit the epiblast is involved in the phagocytosis of the polar trophoblast.
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Affiliation(s)
- B S Williams
- Department of Anatomy and Cellular Biology, Harvard Medical School, Boston, Massachusetts 02115
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Enders AC, Lantz KC, Schlafke S. Differentiation of the inner cell mass of the baboon blastocyst. Anat Rec (Hoboken) 1990; 226:237-48. [PMID: 2301740 DOI: 10.1002/ar.1092260213] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During the blastocyst stage of development in the baboon, the inner cell mass changes from an irregular accumulation of cells within the cavity of the blastocyst to a disk at one side of the blastocyst and finally to a spherical mass of epiblast cells exhibiting a distinct polarity. The cells that will become the primitive endoderm are first seen as flattened but undifferentiated cells on the cavity side of the disk-shaped inner cell mass. After endoderm cells develop their typical cytological characteristics, they extend well beyond the inner cell mass to form parietal endoderm. A basal lamina develops associated with the epiblast cells and mural trophoblast, but not with either parietal or visceral endoderm. Cytological differentiation of inner cell mass cells includes increased numbers of polyribosomes and a change in mitochondria from long, convoluted structures to short, more typical shapes. Evidence that epiblast is polarized is seen by the late zonal blastocyst stage. Apical junctional complexes develop within the center of the epiblast. These junctions presage the development of the potential amniotic cavity. Large vacuoles containing cell debris, some of which contain nuclear fragments, are present at all stages. Extensive cell death occurs during growth of the blastocyst, but the pattern appears to be random and products of cell death are readily phagocytized by adjacent cells.
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Affiliation(s)
- A C Enders
- Department of Human Anatomy, School of Medicine, University of California, Davis 95616
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