PDF(Pubmed)
Abstract：
The fertilization of oocytes ovulated by pigs, sheep, cows, and horses is not considered a limiting factor in successful establishment of pregnancy. Pig, sheep, and cow embryos undergo cleavage to the blastocyst stage, hatch from the zona pellucida, and undergo central-type implantation. Hatched blastocysts of pigs, sheep, and cows transition from tubular to long filamentous forms to establish surface area for exchange of nutrients and gases with the uterus. The equine blastocyst, surrounded by external membranes, does not elongate but migrates throughout the uterine lumen before attaching to the uterine luminal epithelium (LE) to begin implantation. Pregnancy recognition signaling in pigs requires the trophectoderm to express interleukin 1 beta, estrogens, prostaglandin E2, and interferon gamma. Sheep and cow conceptus trophectoderm expresses interferon tau that induces interferon regulatory factor 2 that inhibits transcription of estrogen and oxytocin receptors by uterine epithelia. This prevents oxytocin-induced luteolytic pulses of prostaglandin F2-alpha from regressing the corpora lutea, as well as ensuring the secretion of progesterone required for maintenance of pregnancy. The pregnancy recognition signal produced by equine blastocysts is not known. Implantation in these species requires interactions between extracellular matrix (ECM) proteins and integrins as the conceptus undergoes apposition and firm attachment to the uterine LE. This review provides details with respect to early embryonic development and the transition from spherical to filamentous conceptuses in pigs, sheep, and cows, as well as pre-implantation development of equine blastocysts and implantation of the conceptuses.
摘要：
猪排卵的卵母细胞受精，绵羊,奶牛,马匹不被认为是成功怀孕的限制因素。猪,绵羊,奶牛胚胎经历卵裂到胚泡期，透明带的舱口,并进行中央型植入。猪的孵化胚泡，绵羊,奶牛从管状过渡到长丝状形式，以建立与子宫交换营养和气体的表面积。马囊胚,被外部膜包围，在附着到子宫腔上皮（LE）开始植入之前，不会拉长，但会迁移到整个子宫腔。猪的妊娠识别信号需要滋养外胚层表达白细胞介素1β，雌激素,前列腺素E2和干扰素γ。绵羊和母牛概念滋养外胚层表达干扰素tau，其诱导干扰素调节因子2，该因子抑制子宫上皮对雌激素和催产素受体的转录。这可以防止催产素诱导的前列腺素F2-α的黄体溶解脉冲使黄体消退，以及确保维持妊娠所需的孕酮分泌。由马胚泡产生的妊娠识别信号是未知的。在这些物种中的植入需要细胞外基质（ECM）蛋白和整合素之间的相互作用，因为该概念经历并置并牢固附着于子宫LE。这篇综述提供了有关猪早期胚胎发育以及从球形到丝状概念过渡的详细信息，绵羊,奶牛,以及马囊胚的植入前发育和概念植入。
