Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA.
Biol Reprod. 2021 Apr 1;104(4):771-783. doi: 10.1093/biolre/ioab001.
Endometrial receptivity and embryo implantation processes are a major point of pregnancy failure in many mammalian species, including humans. Although reproductive biology in many carnivore species remains enigmatic, the few that have been studied so far are invaluable comparative models. The goals of this review are to (1) summarize current data on the mechanisms involved in uterine receptivity and embryo implantation in carnivores, including commonalities and differences with other mammalian species and (2) identify research priorities to better understand a key phenomenon in a critical group of mammals. Besides unique reproductive traits in some carnivores (induced vs. spontaneous ovulation in cats, ovulation at the germinal vesicle stage in dogs), preimplantation embryo development is comparable with other orders. However, the timing of implantation varies, especially in species having an embryonic diapause. Mechanisms involved in endometrial receptivity and decidualization still remain to be fully understood, but specific markers have already been identified. Importantly, the use of endogenous hormones to control the ovarian activity may impact endometrial receptivity and subsequent embryo implantation. Next, research efforts should take advantage of advanced technologies to further study embryo implantation in carnivores and to provide more relevant models to reproductive medicine or for the conservation of rare and endangered species.
子宫内膜容受性和胚胎着床过程是许多哺乳动物物种（包括人类）妊娠失败的一个主要原因。尽管许多食肉动物的生殖生物学仍然是个谜，但迄今为止已经研究过的少数几种动物是非常有价值的比较模型。本综述的目的是：(1)总结目前关于食肉动物子宫容受性和胚胎着床机制的研究数据，包括与其他哺乳动物物种的异同；(2)确定研究重点，以更好地了解关键哺乳动物群体中的一个关键现象。除了一些食肉动物的独特生殖特征（猫为诱导性排卵，狗为卵母细胞生发泡期排卵）外，着床前胚胎发育与其他目相似。然而，着床的时间有所不同，特别是在有胚胎休眠的物种中。子宫内膜容受性和蜕膜化的机制仍有待充分了解，但已经确定了特定的标记物。重要的是，使用内源性激素来控制卵巢活动可能会影响子宫内膜的容受性和随后的胚胎着床。接下来，研究工作应该利用先进的技术来进一步研究食肉动物的胚胎着床，并提供更多相关的模型来进行生殖医学研究，或保护稀有和濒危物种。
