Current status of embryo technologies in sheep and goat.
TL;DR: The recent improvements of embryo production and freezing technologies could be used for constitution of flocks without risks of disease transmission and will allow wider propagation of valuable genes in small ruminants populations in the future.
About: This article is published in Theriogenology.The article was published on 2003-01-01. It has received 319 citations till now.
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TL;DR: Transgenesis and cloning are expected to have a significant impact on the future genetic improvement of livestock because of low efficiencies and high costs, their present use is restricted to applications with high returns such as the production of recombinant proteins of pharmaceutical and biomedical interest.
181 citations
TL;DR: Although in morphologically high quality blastocysts of several farm animal species a significant difference exists in the percentages of apoptotic cells between in vivo and in vitro produced embryos, the incidence of apoptosis at the blastocyst stage is at such a low level that it cannot reflect the substantial differences in embryo viability.
168 citations
Cites background or result from "Current status of embryo technologi..."
...Significant improvement has been achieved in recent years in both the in vivo and in vitro production of farm animal embryos [7,18,34,50]....
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...In case of kidding and calving, the ET rates were respectively 71 and 76% for in vivo produced embryos, and 47 [7] and 30% [31,39] for in vitro produced embryos....
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...The embryos derived from such rescued oocytes are known to have a reduced embryonic developmental potential [7,8,18] and this may have led to a lower percentage of embryos of excellent morphology in the species where superovulation was induced compared to the equine....
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TL;DR: Nuclear DNA confirmed that the clone was genetically identical to the bucardo's donor cells, making it the first animal born from an extinct subspecies.
153 citations
Cites methods from "Current status of embryo technologi..."
...The treatment, consisting in a combination of decreasing doses of highly purified FSH with an injection of LH at the end of the progestagen treatment, has been successfully used in superovulation of domestic goats for embryo transfer purposes [19]....
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TL;DR: Emerging data indicate that the main causes of variability are related to endocrine and ovarian factors, and so the number of studies and procedures addressing a better understanding and control of these factors may be increased in the future.
Abstract: This review offers an overview of the basic characteristics of in vivo embryo technologies, their current status, the main findings and the advances gained in recent years, and the outstanding subjects for increasing their efficiency. The use of superovulation and embryo transfer procedures remains affected by a high variability in the ovulatory response to hormonal treatment and by a low and variable number of transferable embryos and offspring obtained. This variability has been classically identified with both extrinsic (source, purity of gonadotrophins and protocol of administration) and intrinsic factors (breed, age, nutrition and reproductive status), which are reviewed in this paper. However, emerging data indicate that the main causes of variability are related to endocrine and ovarian factors, and so the number of studies and procedures addressing a better understanding and control of these factors may be increased in the future. The accomplishment of this objective, the improvement of procedures for embryo conservation and for the selection and management of recipient females, will allow further development and application of this technology.
140 citations
TL;DR: Using ultrasonography a new field has been opened and surely successful output will be forthcoming in the next years to improve reproductive management of the goat, the fastest growing ruminant population in the world.
133 citations
Cites background from "Current status of embryo technologi..."
...However, terminal follicular growth was impaired in goats and the beneficial effect of this treatment on the ovulation rate is negated by an increase in the proportion of unfertilised ova and degenerated embryos (Cognie et al., 2003)....
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References
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TL;DR: Investigation of sheep zygote development of amino acids, ammonium, vitamins, and culture of embryos in groups in Synthetic Oviduct Fluid medium supplemented with BSA found indirect evidence that ruminant embryos utilize amino acids to a greater extent than do rodent embryos.
Abstract: The aim of this study was to develop a serum-free culture system that could support high levels of cleavage and blastocyst formation from sheep zygotes developed in vitro. To this end, we investigated the effects on sheep zygote development of amino acids, ammonium, vitamins, and culture of embryos in groups in Synthetic Oviduct Fluid (SOF) medium supplemented with BSA (32 mg/ml). The inclusion of amino acids in the culture medium had no effect on the percentage of embryos arrested at the 8-16-cell stage when embryos were cultured singly in the same drop of medium for 6 days (43% in SOF; 41% in SOF+amino acids). However, in medium containing all Eagle's amino acids, replacing the culture medium every 48 h to alleviate ammonium toxicity significantly decreased the number of arrested embryos (6%; p < 0.05) and significantly increased blastocyst cell number (52 cells in SOF; 105 cells in SOF+amino acids; p < 0.01) and the number of embryos developing to the blastocyst stage (29% in SOF; 67% in SOF+amino acids; p < 0.05). When the medium was renewed every 48 h, nonessential amino acids and glutamine also significantly decreased the number of arrested embryos (p < 0.05). Culturing embryos singly or in groups in SOF medium with all Eagle's amino acids that was renewed every 48 h resulted in significant increases in blastocyst hatching and mean cell number (47%, 31%, and 79%; 105, 136, and 173 cells for embryos cultured singly, in groups of 2, and in groups of 4, respectively). After culture in groups of 4, blastocyst cell numbers were equivalent to in vivo-developed controls (160 cells) and significantly greater than those developed in serum (103 cells; p < 0.01). Analysis of blastocyst metabolism, expressed on a per-cell basis, revealed that amino acids did not affect either glucose uptake or lactate production, whereas the addition of amino acids and vitamins resulted in a significant increase in both parameters (p < 0.01). A similar response was observed in serum-derived blastocysts. Ammonium production by sheep blastocysts after culture in the presence of amino acids was significantly greater than that produced by mouse blastocysts, indirect evidence that ruminant embryos utilize amino acids to a greater extent than do rodent embryos.(ABSTRACT TRUNCATED AT 400 WORDS)
558 citations
TL;DR: It is concluded that during the first 3 days after fertilization cleavage will progress at a normal rate on different feeder-layers but oviduct cells appear to be required for the acquisition of full embryonic viability.
Abstract: To examine the effects of somatic cell support on the cleavage and viability of fertilized sheep eggs, 434 pronucleate eggs were co-cultured for 3 or 6 days on oviduct cells or fibroblasts and 77 eggs were cultured in medium alone. During the first 3 days in culture 95% of the single-celled eggs cleaved regularly to non-compacted morulae on either of the feeder-layers but only 13% underwent similar regular cleavage in medium alone. Despite the identical cleavage rates in the co-culture groups, only 33% of embryos grown on fibroblasts as compared with 80% of embryos grown on oviduct cells were fully viable as judged by their ability to develop normally after transfer to recipient animals. The viability of embryos in the oviduct group was equal to that obtained after the direct transfer of morulae from donor to recipient sheep. After 6 days in culture 42% of embryos co-cultured with oviduct cells developed into expanded blastocysts as compared with only 4.5% cultured on fibroblasts. In both co-culture groups virtually all the remaining embryos blocked during the 4th cleavage. When transferred, 30% of blastocysts grown from the pronucleate stage on oviduct cells were viable. We conclude that: (1) during the first 3 days after fertilization cleavage will progress at a normal rate on different feeder-layers but oviduct cells appear to be required for the acquisition of full embryonic viability.(ABSTRACT TRUNCATED AT 250 WORDS)
494 citations
TL;DR: Messenger RNA phenotyping of genes essential in early development provides a useful tool to assess the normality of the produced embryos and a tool to optimize in vitro culture conditions for bovine embryos.
487 citations
TL;DR: Developmental capacity after culture was further demonstrated by the birth of lambs from 63% of blastocysts derived from oocytes matured in vitro; 52% of control blastocyst developed to lambs after transfer.
Abstract: Oocytes removed from, or retained within, non-atretic and atretic follicles of different sizes were cultured for 24 h in the presence of a variety of hormones in an attempt to identify the factors affecting oocyte maturation in vitro. Resumption of meiosis was assessed morphologically; the developmental capacity of oocytes after culture was determined by transfer to the oviducts of inseminated ewes. About 70% of oocytes cultured after removal from follicles of different sizes resumed meiosis in vitro, but they did not undergo normal development after transplantation. Oocytes cultured within the follicle in hormone-free medium remained at the germinal vesicle stage. In the presence of FSH and LH some oocytes reached the second meiotic metaphase: 19% in small (2-3 mm diam.) and 73% in larger (3-5 mm diam.) non-atretic follicles, and 54% in small and 45% in larger atretic follicles. Less than 5% of oocytes cultured in follicles developed into normal blastocysts after transplantation when either no hormone or only FSH and LH were added to the culture medium. The addition of oestradiol-17beta to medium containing FSH (2 mug/ml) and LH (1 mug/ml) resulted in the development to blastocysts of 26% of oocytes from small non-atretic follicles, 46% from large non-atretic follicles and 50% from atretic follicles. Blastocyst formation was greatly depressed and fragmentation rate signinificantly increased with concentrations of 10 mugFSH/ml and 2 mug LH/ml. Developmental capacity after culture was further demonstrated by the birth of lambs from 63% of blastocysts derived from oocytes matured in vitro; 52% of control blastocysts developed to lambs after transfer.
452 citations