Preimplantation development of in vitro-matured and in vitro-fertilized ovine zygotes: comparison between coculture on oviduct epithelial cell monolayers and culture under low oxygen atmosphere.
01 Apr 1994-Biology of Reproduction (Society for the Study of Reproduction)-Vol. 50, Iss: 4, pp 715-724
TL;DR: Two distinct culture environments are characterized, each capable of supporting the development of high frequencies of unselected IVMF zygotes to the blastocyst stage in vitro, and survival of the embryo under a reduced oxygen atmosphere is investigated.
Abstract: The roles of medium composition, serum source, embryo coculture, and culture under low O2 conditions on the development of in vitro-matured and in vitro-fertilized (IVMF) ovine zygotes were investigated in three separate experiments. In the first experiment, the proportion of cocultured IVMF zygotes developing to the blastocyst stage was significantly higher (38.0% vs. 3.5%; p < 0.05) than that of non-cocultured zygotes treated within three embryo culture media (TCM-199 + 10% fetal bovine serum [FBS]; bicarbonate-buffered, glucose-free synthetic oviduct fluid medium [mod-SOFM] + 10% FBS; and bicarbonate-buffered BSA-free Tyrode's salt solution [mod-TALP] + 10% FBS) under a 5% CO2 atmosphere in air. In a second experiment, a significantly higher (p < 0.05) proportion of cocultured zygotes placed in TCM-199 medium survived to the blastocyst stage (37.4% blastocysts vs. 23.4% in mod-SOFM). No significant effect of serum (FBS vs. human serum [HS]) was observed on embryonic development, but coculture was confirmed to exert a significant influence on development to the blastocyst stage. In the final experiment, survival of the embryo under a reduced oxygen (5% CO2:5% O2:90% N2) atmosphere was investigated. In contrast to results in the initial experiments, embryonic survival was significantly higher (p < 0.05) in the non-cocultured treatment groups (21.9% blastocysts vs. 0.4% for cocultured zygotes). Serum source also had a significant (p < 0.05) influence upon the development of non-cocultured zygotes: 32.3% of zygotes cultured with HS progressed to the blastocyst stage vs. 11.5% of zygotes cultured in FBS-supplemented medium. These results have characterized two distinct culture environments, each capable of supporting the development of high frequencies of unselected IVMF zygotes to the blastocyst stage in vitro.
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TL;DR: Compounds such as ethylenediamine tetraacetic acid (EDTA), NaN(3) and 2,4-dinitrophenol have been shown to increase embryo development and quality of resulting embryos, demonstrating that the process of ATP production is a key regulator of in vitro embryo development.
199 citations
Cites background from "Preimplantation development of in v..."
...Furthermore, positive factors influencing embryo development, such as a low O environment and low glucose levels, which have been attributed to the success2 Ž .of co-culture conditions Watson et al., 1994b; Edwards et al., 1997 , were first identified using defined systems....
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TL;DR: Differences in lambing and calving rates and the reports of abnormal fetal development from embryos produced in vitro are of major concern, as they suggest that the in vitro environment may affect subsequent developmental physiology.
Abstract: In vitro production of ruminant embryos has become routine and is increasingly available as a commercial service to dairy, meat and wool producers. However, the efficiency of producing viable embryos and the development of such embryos after transfer to recipients are perceived to be inferior to that which occurs in vivo. The present review outlines the biochemical and morphological similarities and differences between embryos produced in vitro and those produced in vivo. Some measures of metabolism are not markedly different between in vitro- and in vivo-derived blastocysts. However, at a cellular and subcellular level, differences in metabolism, morphology and ultrastructure have been described, as has susceptibility to manipulation and cryopreservation. Most importantly are the differences in lambing and calving rates and the reports of abnormal fetal development from embryos produced in vitro. These latter observations are of major concern, as they suggest that the in vitro environment may affect subsequent developmental physiology. At the extreme, these effects may not be expressed until adult life. Further efforts to improve the efficiency of in vitro embryo production must be accompanied by a commitment to assess the long-term consequences of these procedures.
175 citations
TL;DR: The process of animal production by nuclear transfer is discussed and in particular changes in the methodology which have increased development and survival, simplified or increased robustness of the technique are discussed.
169 citations
TL;DR: Although culture under 5% O2 leads to slightly improved preim implantation embryonic viability, this effect is either too marginal to result in higher pregnancy rates, or low O2 concentrations exert an effect during the later stages of preimplantation development only.
Abstract: In this prospective randomized study on 1380 consecutive in-vitro fertilization (IVF) treatments, the results were compared of culture of human oocytes and embryos for the first 2 or 3 days of development in microdroplets of medium under oil using a gas phase containing either atmospheric (approximately 20%) or reduced (5%) O2 concentrations. No significant differences were found between the two groups cultured under either 5% or 20% O2 in rates of fertilization (60 versus 61%, respectively), embryo development at day 2 or 3, pregnancy (26.6 versus 25.4%, respectively), and implantation (13.4 versus 14.0%, respectively). Culture of surplus embryos under 5% O2 resulted in a significantly higher mean incidence of blastocyst formation per cycle as compared to the 20% O2 group (25.8 +/- 2.0 versus 20.4 +/- 1.9, respectively). The mean number of cells of embryos classified as blastocysts by microscopic observation of a blastocoel was significantly higher in the 5% O2 group as compared to the 20% O2 group, both in blastocysts fixed on day 5 (39.8 +/- 1.7 versus 31.9 +/- 1.9, respectively), as well as those fixed on day 6 (45.6 +/- 2.6 versus 33.7 +/- 3.4, respectively). This difference was due to the fact that significantly more blastocysts of the 20% O2 group had an abnormal low cell number of < 25 as compared to the 5% O2 group, both in blastocysts fixed on day 5 (39 versus 22%, respectively), as well as those fixed on day 6 (43 versus 22%, respectively). To conclude, although culture under 5% O2 leads to slightly improved preimplantation embryonic viability, this effect is either too marginal to result in higher pregnancy rates, or low O2 concentrations exert an effect during the later stages of preimplantation development only.
162 citations
Cites result from "Preimplantation development of in v..."
...When cow or sheep embryos are co-cultured with other cells, 20% O2 is found to give better results as compared to 5% O2 in several studies (Fukui et al., 1991; Voelkel and Hu, 1992; Watson et al., 1994)....
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References
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