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Julia G, Barbara KM, Sebastian S, Joanna K, Agnieszka N, Julianna Ł, Elżbieta K, Monika BP. Extracellular vesicles from follicular fluid may improve the nuclear maturation rate of in vitro matured mare oocytes. Theriogenology 2022; 188:116-124. [DOI: 10.1016/j.theriogenology.2022.05.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/25/2022] [Accepted: 05/25/2022] [Indexed: 11/27/2022]
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Morris LHA. The development of in vitro embryo production in the horse. Equine Vet J 2018; 50:712-720. [DOI: 10.1111/evj.12839] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 03/22/2018] [Indexed: 11/29/2022]
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Influence of follicle size, methods of retrieval on oocytes yield and morphology in Egyptian Jennies ovaries with special reference to maturation rate in vitro. Vet Res Commun 2014; 38:287-95. [DOI: 10.1007/s11259-014-9617-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 09/05/2014] [Indexed: 10/24/2022]
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Galli C, Duchi R, Colleoni S, Lagutina I, Lazzari G. Ovum pick up, intracytoplasmic sperm injection and somatic cell nuclear transfer in cattle, buffalo and horses: from the research laboratory to clinical practice. Theriogenology 2014; 81:138-51. [PMID: 24274418 DOI: 10.1016/j.theriogenology.2013.09.008] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/06/2013] [Accepted: 09/07/2013] [Indexed: 12/29/2022]
Abstract
Assisted reproductive techniques developed for cattle in the last 25 years, like ovum pick up (OPU), intracytoplasmic sperm injection (ICSI), and somatic cell nuclear transfer, have been transferred and adapted to buffalo and horses. The successful clinical applications of these techniques require both the clinical skills specific to each animal species and an experienced laboratory team to support the in vitro phase of the work. In cattle, OPU can be considered a consolidated technology that is rapidly outpacing conventional superovulation for embryo transfer. In buffalo, OPU represents the only possibility for embryo production to advance the implementation of embryo-based biotechnologies in that industry, although it is still mainly in the developmental phase. In the horse, OPU is now an established procedure for breeding from infertile and sporting mares throughout the year. It requires ICSI that in the horse, contrary to what happens in cattle and buffalo, is very efficient and the only option because conventional IVF does not work. Somatic cell nuclear transfer is destined to fill a very small niche for generating animals of extremely high commercial value. The efficiency is low, but because normal animals can be generated it is likely that advancing our knowledge in that field might improve the technology and reduce its cost.
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Affiliation(s)
- Cesare Galli
- Avantea, Laboratory of Reproductive Technologies, 26100 Cremona, Italy; Department of Veterinary Medical Sciences, University of Bologna, Italy; Fondazione Avantea, Cremona, Italy.
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Equine bone marrow mesenchymal or amniotic epithelial stem cells as feeder in a model for the in vitro culture of bovine embryos. ZYGOTE 2010; 20:45-51. [DOI: 10.1017/s0967199410000493] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SummaryVarious studies have shown that the in vitro culture environment is one of the key determinants of the blastocyst output. In the present study we investigated the effects of co-culturing bovine embryos with equine bone marrow mesenchymal stem cells (BM-MSCs) or equine amniotic epithelial stem cells (AE-SCs) on in vitro blastocysts development. BM specimens were obtained aseptically from sternal aspirates of horses under local anaesthesia and the isolated cells were resuspended in Dulbecco Modified Earle's Medium supplemented with 10 ng/ml of basic fibroblast growth factor (bFGF). Amniotic membranes were obtained from fresh placentas and, to release the AE cells, amniotic fragments were incubated with 0.05% trypsin for 45 min. Separated AE cells were plated in standard culture medium containing 10 ng/ml epidermal growth factor (EGF). Seven hundred and five cumulus–oocyte complexes were used and, after IVM and IVF, cumulus-free presumptive zygotes were randomly transferred into one of three co-culture systems in which they were cultured up to day 7: (1) co-culture with cumulus cells (control); (2) co-culture with BM-MSCs; and (3) co-culture with AE-SCs. Statistical analyses were performed by ANOVA. Blastocyst developmental rates were significantly different (p < 0.001) between control, AE-SCs and BM-MSCs (respectively 35.45, 41.84 and 30.09%). In conclusion, the AE-SC monolayer create a more suitable microenvironment necessary for inducing local cell activation and proliferation of the growing embryos in comparison with BM-MSCs and cumulus cells. It can be suggested that these cells secrete biologically active substances, including signalling molecules and growth factors of epithelial nature, different to those of the BM cells of mesenchymal origin.
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Spizziri B, Fox M, Bruemmer J, Squires E, Graham J. Cholesterol-loaded-cyclodextrins and fertility potential of stallions spermatozoa. Anim Reprod Sci 2010; 118:255-64. [DOI: 10.1016/j.anireprosci.2009.08.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 07/20/2009] [Accepted: 08/11/2009] [Indexed: 11/25/2022]
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Galli C, Lagutina I, Duchi R, Colleoni S, Lazzari G. Somatic Cell Nuclear Transfer in Horses. Reprod Domest Anim 2008; 43 Suppl 2:331-7. [DOI: 10.1111/j.1439-0531.2008.01181.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Matsukawa K, Akagi S, Adachi N, Sato F, Hasegawa T, Takahashi S. In vitro development of equine oocytes from preserved ovaries after intracytoplasmic sperm injection. J Reprod Dev 2007; 53:877-85. [PMID: 17510527 DOI: 10.1262/jrd.18167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, we evaluated the meiotic competence of equine oocytes from ovaries preserved for one day. We also investigated fertilization, cleavage rate, developmental competence and freezability of equine embryos after intracytoplasmic sperm injection (ICSI). After collection from ovaries, the oocytes were classified into two groups comprised of those having compact cumulus layers (Cp) or those having expanded cumulus layers (Ex). Oocytes with a first polar body were subjected to fertilization by ICSI using frozen-thawed stallion spermatozoa and were then cultured in CR1aa medium. The rates of metaphase II-stage oocytes, normal fertilization and cleavage were not significantly different between the two oocyte categories (38.5, 70.0 and 48.7% for CP and 43.5, 60.0 and 58.8% for Ex, respectively). However, the blastocyst development rate of Ex was significantly (P<0.05) higher than that of Cp (25.5 vs. 7.7%). Three Cp-derived and 12 Ex-derived early blastocysts were cryopreserved using the slow cooling protocol, and all of them developed to hatching blastocysts after thawing. These results suggest that equine oocytes fertilized by ICSI can develop to the preimplantation stage in culture conditions similar to those used in the bovine. Furthermore, the Ex oocytes had higher developmental competence than the Cp oocytes, and the in vitro-produced blastocysts had high viability after freezing and thawing.
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Affiliation(s)
- Kazutsugu Matsukawa
- Department of Animal Breeding and Reproduction, National Institute of Livestock and Grassland Science, Tsukuba, Japan.
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Galli C, Colleoni S, Duchi R, Lagutina I, Lazzari G. Developmental competence of equine oocytes and embryos obtained by in vitro procedures ranging from in vitro maturation and ICSI to embryo culture, cryopreservation and somatic cell nuclear transfer. Anim Reprod Sci 2006; 98:39-55. [PMID: 17101246 DOI: 10.1016/j.anireprosci.2006.10.011] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Development of assisted reproductive technologies in horses has been relatively slow compared to other domestic species, namely ruminants and pigs. The scarce availability of abattoir ovaries and the lack of interest from horse breeders and breed associations have been the main reasons for this delay. Progressively though, the technology of oocyte maturation in vitro has been established followed by the application of ICSI to achieve fertilization in vitro. Embryo culture was initially performed in vivo, in the mare oviduct or in the surrogate sheep oviduct, to achieve the highest embryo development, in the range of 18-36% of the fertilised oocytes. Subsequently, the parallel improvement of in vitro oocyte maturation conditions and embryo culture media has permitted high rates of embryo development from in vitro matured and in vitro cultured ICSI embryos, ranging from 5 to 10% in the early studies to up to 38% in the latest ones. From 2003, with the birth of the first cloned equids, the technology of somatic cell nuclear transfer has also become established due to improvement of the basic steps of embryo production in vitro, including cryopreservation. Pregnancy and foaling rates are still estimated based on a small number of in vitro produced equine embryos transferred to recipients. The largest set of data on non-surgical embryo transfer of in vitro produced embryos, from ICSI of both abattoir and in vitro-matured Ovum Pick Up (OPU) oocytes, and from somatic cell nuclear transfer, has been obtained in our laboratory. The data demonstrate that equine embryos produced by OPU and then cryopreserved can achieve up to 69% pregnancy rate with a foaling rate of 83%. These percentages are reduced to 11 and 23%, respectively, for cloned embryos. In conclusion, extensive evidence exists that in vitro matured equine oocytes can efficiently develop into viable embryos and offspring.
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Affiliation(s)
- C Galli
- Laboratorio di Tecnologie della Riproduzione, Istituto Sperimentale Italiano Lazzaro Spallanzani, CIZ s.r.l., Via Porcellasco 7f, 26100 Cremona, Italy.
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Choi YH, Love LB, Varner DD, Hinrichs K. Holding immature equine oocytes in the absence of meiotic inhibitors: Effect on germinal vesicle chromatin and blastocyst development after intracytoplasmic sperm injection. Theriogenology 2006; 66:955-63. [PMID: 16574209 DOI: 10.1016/j.theriogenology.2006.01.064] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 01/22/2006] [Indexed: 10/24/2022]
Abstract
Holding immature oocytes before the onset of maturation simplifies oocyte transport and aids in scheduling later manipulations. We report here a method for holding equine oocytes in the absence of meiotic inhibitors. In Experiment 1, immature oocytes with expanded cumuli were cultured at 38.2 degrees C in medium containing cycloheximide, or were held at room-temperature in M199 with Hanks' salts, for 16-18 h before maturation. Control oocytes were matured immediately after recovery. Oocytes were fertilized by intracytoplasmic sperm injection and cultured for 4d. Embryo development was not different among treatments. In Experiment 2, oocytes were treated as in Experiment 1, but embryos were cultured for 7.5d. Blastocyst development was significantly lower in the cycloheximide-treated group than in controls (7% versus 30%) with the room-temperature group intermediate (16%). In Experiment 3, oocytes were cultured at 38.2 degrees C in medium containing roscovitine, or were held at room temperature in sealed glass vials in a mixture of 40% M199 with Earle's salts, 40% M199 with Hanks' salts, and 20% FBS (EH treatment) for 16-18 h, before maturation, sperm injection, and embryo culture for 7.5d. Blastocyst development of oocytes in the EH treatment was significantly higher than that for roscovitine-treated oocytes (34% versus 12%), but not significantly different from that for controls (25%). Oocytes in the EH treatment did not mature during holding (70% germinal vesicle stage after 18 h holding). Whereas culture with cycloheximide or roscovitine of equine oocytes with expanded cumuli reduced subsequent blastocyst formation, these oocytes could be held in a modified M199 at room temperature overnight without adverse affecting meiotic or developmental competence.
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Affiliation(s)
- Y H Choi
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Science, Texas A&M University, College Station, TX 77843, USA
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Abstract
Intracytoplasmic sperm injection (ICSI) has recently become efficient enough to be considered for clinical use. With ICSI, one spermatozoa is injected into a mature oocyte. Harvesting of an oocyte ex vivo, followed by ICSI and transfer of the fertilized oocyte to the oviduct, may be applicable when semen quality is insufficient for standard insemination. Sperm injection, followed by in vitro embryo culture to the blastocyst stage, may be used in cases where multiple oocytes are to be fertilized (e.g. when oocytes are collected post-mortem). Nuclear transfer (cloning) of horses is possible but still inefficient; however, commercial companies currently will culture and store cells from privately owned animals for a reasonable fee. Horse owners are beginning to realize the potential of cloning for salvaging valuable equine genetics that may otherwise be lost.
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Affiliation(s)
- Katrin Hinrichs
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, 4466 TAMU, College Station, TX 77843-4466, USA.
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Hinrichs K, Choi YH, Love LB, Varner DD, Love CC, Walckenaer BE. Chromatin Configuration Within the Germinal Vesicle of Horse Oocytes: Changes Post Mortem and Relationship to Meiotic and Developmental Competence1. Biol Reprod 2005; 72:1142-50. [PMID: 15647456 DOI: 10.1095/biolreprod.104.036012] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We evaluated the relationship of initial chromatin configuration to time of oocyte recovery and to nuclear maturation after culture in horse oocytes having compact (Cp) and expanded (Ex) cumuli. In addition, we evaluated the effect of oocyte type, time of recovery, and duration of culture on blastocyst development after intracytoplasmic sperm injection. In oocytes collected within 1 h of slaughter, fibrillar and intermediate chromatin configurations were more prevalent in Cp than in Ex oocytes (68% and 12%, respectively). In Cp oocytes collected after a 5- to 9-h delay, the proportions in the fibrillar and intermediate configurations decreased significantly, and the proportions of degenerating and homogeneously fluorescent configurations increased. When cultured, 20% of oocytes classified as having fibrillar chromatin resumed meiosis, whereas 82% of intermediate and 81% to 86% of condensed chromatin oocytes did so. Meiotic resumption was higher in oocytes recovered immediately after slaughter, but these oocytes took longer to mature. Duration of maturation significantly affected blastocyst development rates in Cp oocytes recovered after a delay (13% and 38% for oocytes matured 24 and 36 h, respectively). Oocytes recovered after a delay had higher blastocyst development rates than did those collected immediately after slaughter. We conclude that the fibrillar and intermediate chromatin configurations may degenerate during ovary storage, resulting in decreased maturation rates, especially of Cp oocytes. Time of oocyte recovery and duration of maturation significantly affect the rate of blastocyst development. Oocytes with Cp and Ex cumuli have similar developmental competence to the blastocyst stage.
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Affiliation(s)
- K Hinrichs
- Department of Veterinary, College of Veterinary Medicine, Texas A&M University, Texas 77843-4466, USA.
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Gil L, Saura S, Echegaray A, Martinez F, de Blas I, Akourki A, Gonzalez N, Espinosa E, Josa A. Effect of the in vitro maturation medium on equine oocytes: comparison of follicular fluid and oestrous mare serum. Acta Vet Hung 2005; 53:241-8. [PMID: 15959982 DOI: 10.1556/avet.53.2005.2.9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The present study evaluated the effect of supplementing the medium used to mature equine oocytes in vitro with oestrous mare serum (EMS) or horse follicular fluid (HFF). To this end, 144 ovaries were obtained from mares aged 16-21 months and transported to the laboratory in Dulbecco's phosphate buffered saline (D-PBS) at 30 degrees C. Oocytes were harvested from the ovaries by slicing, and then selected for in vitro maturation (IVM) according to the number of cumulus cell layers and the characteristics of the cytoplasm. The selected oocytes were washed three times in TCM199 medium plus HEPES (TCM-199H) or in the same medium plus glutamine (TCM-199G), then matured in vitro in six study groups established according to the in vitro maturation (IVM) treatment to see possible interactions between HEPES and glutamine on other supplements: Ten percent EMS was added to two of these media (TCM-199H+EMS and TCM-199G+EMS) and 10% HFF was added to the media in two other groups (TCM-199H+HFF and TCM-199G+HFF). IVM was performed at 38.5 degrees C for 40 h in a controlled atmosphere (5% CO2, 95% relative humidity). The findings indicate that the presence of EMS or HFF in the TCM-199H medium gives rise to the best results in terms of the proportions of oocytes reaching maturity (37.7% and 36.8%, respectively). The values obtained with EMS and HFF were statistically similar to each other but differed from the other treatments. The media containing glutamine led to the highest proportions of degenerated oocytes.
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Affiliation(s)
- Lydia Gil
- Department of Veterinary Pathology, Faculty of Veterinary Medicine, University of Zaragoza, Spain.
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Choi YH, Roasa LM, Love CC, Varner DD, Brinsko SP, Hinrichs K. Blastocyst Formation Rates In Vivo and In Vitro of In Vitro-Matured Equine Oocytes Fertilized by Intracytoplasmic Sperm Injection1. Biol Reprod 2004; 70:1231-8. [PMID: 14695908 DOI: 10.1095/biolreprod.103.023903] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
This study was conducted to evaluate in vivo and in vitro development of in vitro-matured equine oocytes fertilized by intracytoplasmic sperm injection. Oocytes were collected from slaughterhouse-derived ovaries, matured in vitro, and injected with frozen-thawed stallion sperm. In vivo development was assessed after transfer of injected oocytes to the oviducts of recipient mares. Mares were killed 7.5-8.5 days after transfer and the uterus and oviducts flushed for embryo recovery. Of 132 injected oocytes transferred, 69 (52%) were recovered; of these, 25 (36%) were blastocysts with a blastocoele and capsule. In vitro development was assessed in three culture systems. Culture of zygotes in modified Chatot, Ziomek, Bavister medium with BSA containing either 5.5 mM glucose for 7.5 days or 0.55 mM glucose for 3 days, followed by 3 mM glucose for 2 days, then 4.3 mM glucose for 2.5 days, did not result in blastocyst formation. Culture of zygotes in Dulbecco modified Eagle medium (DMEM)/F-12 with 10% fetal bovine serum with and without coculture with equine oviductal epithelial explants yielded 16% and 15% blastocyst development, respectively. Development to blastocyst was significantly lower in G1.3/2.3/BSA than in DMEM/F-12/BSA or in either medium with 10% added serum (2% vs. 18%, 18% or 20%; P < 0.05), suggesting that requirements for equine embryo development differ from those for other species. These results indicate that in vitro-matured equine oocytes are sufficiently competent to form 36% blastocysts in an optimal environment (in vivo). While we identified an in vitro culture system that provided repeatable blastocyst development without coculture, this yielded only half the rate of development achieved in vivo.
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Affiliation(s)
- Y H Choi
- Department of Veterinary Physiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA
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Tremoleda JL, Stout TAE, Lagutina I, Lazzari G, Bevers MM, Colenbrander B, Galli C. Effects of in vitro production on horse embryo morphology, cytoskeletal characteristics, and blastocyst capsule formation. Biol Reprod 2003; 69:1895-906. [PMID: 12904313 DOI: 10.1095/biolreprod.103.018515] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Blastocyst formation rates during horse embryo in vitro production (IVP) are disappointing, and embryos that blastulate in culture fail to produce the characteristic and vital glycoprotein capsule. The aim of this study was to evaluate the impact of IVP on horse embryo development and capsule formation. IVP embryos were produced by intracytoplasmic sperm injection of in vitro matured oocytes and either culture in synthetic oviduct fluid (SOF) or temporary transfer to the oviduct of a ewe. Control embryos were flushed from the uterus of mares 6-9 days after ovulation. Embryo morphology was evaluated with light microscopy, and multiphoton scanning confocal microscopy was used to examine the distribution of microfilaments (AlexaFluor-Phalloidin stained) and the rate of apoptosis (cells with fragmented or terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling-positive nuclei). To examine the influence of culture on capsule formation, conceptuses were stained with a monoclonal antibody specific for capsular glycoproteins (OC-1). The blastocyst rate was higher for zygotes transferred to a sheep's oviduct (16%) than for those cultured in SOF (6.3%). Day 7 IVP embryos were small and compact with relatively few cells, little or no blastocoele, and an indistinct inner cell mass. IVP embryos had high percentages of apoptotic cells (10% versus 0.3% for in vivo embryos) and irregularly distributed microfilaments. Although they secreted capsular glycoproteins, the latter did not form a normal capsule but instead permeated into the zona pellucida or remained in patches on the trophectodermal surface. These results demonstrate that the initial layer of capsule is composed of OC-1-reactive glycoproteins and that embryo development ex vivo is retarded and aberrant, with capsule formation failing as a result of failed glycoprotein aggregation.
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Affiliation(s)
- Jordi L Tremoleda
- Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CM Utrecht, The Netherlands.
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Choi YH, Love CC, Varner DD, Love LB, Hinrichs K. Effects of gas conditions, time of medium change, and ratio of medium to embryo on in vitro development of horse oocytes fertilized by intracytoplasmic sperm injection. Theriogenology 2003; 59:1219-29. [PMID: 12527070 DOI: 10.1016/s0093-691x(02)01164-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study was conducted to evaluate the effects of two different gas conditions (5% CO(2) in air or 5% CO(2), 5% O(2), 90% N(2), mixed gas), time of medium change (Day 3 or 4) and ratio of medium to embryo (2, 5 or 10 microl per presumptive zygote) on the development of horse oocytes fertilized by intracytoplasmic sperm injection and cultured in G1.2/2.2 medium. Oocytes from slaughterhouse-derived ovaries were matured in vitro for 24 h and fertilized by injection of frozen-thawed sperm using micromanipulation with a Piezo drill. Presumptive zygotes were randomly assigned to 5% CO(2) in air or mixed gas and fixed after 96 h of culture. Cleavage rates between two gas conditions were similar (67 and 63%), but the mean nucleus number of embryos in the mixed gas treatment was significantly (P<0.05) higher than that of embryos cultured in 5% CO(2) in air (15.2 versus 7.0, respectively). Further experiments were done with mixed gas incubation. Development of embryos was compared after change from G1.2 to G2.2 medium at Day 3 or 4. There was no significant difference in cleavage rate (56 and 65%, respectively) or development to the blastocyst stage after 7 days of culture (5% and 46%, respectively) between embryos changed on different days. To evaluate the effect of the ratio of medium to embryo, zygotes were cultured at a ratio of 2, 5 or 10 microl medium per zygote. There were no significant differences among ratio treatments in rates of cleavage or development to blastocyst.
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Affiliation(s)
- Young-Ho Choi
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4466, USA
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