Department of Biology of Reproduction, Biological and Health Sciences Division, Universidad Autónoma Metropolitana, Iztapalapa Unit, Iztapalapa, Mexico.
Department of Agriculture and Animal Production, Biological and Health Sciences Division, Universidad Autónoma Metropolitana, Xochimilco Unit, Mexico City, Mexico.
Vet Med Sci. 2020 Aug;6(3):382-392. doi: 10.1002/vms3.242. Epub 2020 Jan 29.
The developmental dynamics of cloned Mexican bighorn sheep (Ovis canadensis mexicana) embryos were evaluated based on morphological quality standards. Categories determined by standards were correlated with the embryonic development stage, number of nuclei and viability. The results showed no differences in the blastocyst rate between the experimental (cloned Mexican bighorn sheep embryos) and control (parthenogenetic domestic sheep embryos) groups (p > .05), while type IV fragmentation was higher in clones (p < .05). The standards allowed for the identification of embryos that divided at least once or fragmented after 24 hr of culture. The highest percentage of morulae appeared at 96 hr, the final stages of development: nonsegmented, blocked, fragmented and blastocysts appeared at 192 hr. Embryonic quality decreased over time, making 96 hr the ideal time point to predict the final morphological quality of embryos. Nuclear staining of the morulae and blastocysts showed that higher embryo quality was associated with a higher percentage of normal and viable blastomeres. The evaluated criteria allowed for descriptions of the dynamics, stage and quality of cloned Mexican bighorn sheep embryos with a high degree of reliability. In addition, developmental anomalies, including fragmentation, multinucleation and blocking, were identified.
基于形态质量标准评估了克隆墨西哥羊（Ovis canadensis mexicana）胚胎的发育动态。标准确定的类别与胚胎发育阶段、核数和活力相关。结果表明，实验组（克隆墨西哥羊胚胎）和对照组（孤雌生殖的家养绵羊胚胎）的囊胚率没有差异（p>.05），而克隆胚胎的 IV 型碎片率更高（p<.05）。该标准可识别至少分裂一次或在培养 24 小时后发生碎片的胚胎。96 小时时出现最多的桑葚胚，最终的发育阶段：未分节、阻滞、碎片化和囊胚出现在 192 小时。胚胎质量随时间下降，因此 96 小时是预测胚胎最终形态质量的理想时间点。桑椹胚和囊胚的核染色显示，较高的胚胎质量与正常和有活力的卵裂球的比例较高相关。评估标准可以高度可靠地描述克隆墨西哥羊胚胎的动态、阶段和质量。此外，还鉴定了发育异常，包括碎片化、多核化和阻滞。
