Beyes M, Nause N, Bleyer M, Kaup F-J, Neumann S
Institute of Veterinary Medicine, Georg-August-Universität, Göttingen, Germany.
Platform Degenerative Diseases, German Primate Center, Göttingen, Germany.
Anat Histol Embryol. 2017 Dec;46(6):582-591. doi: 10.1111/ahe.12315. Epub 2017 Sep 27.
The embryonic stage of development is defined as the period between fertilization and the establishment of most of the organ systems by the end of this period. Development in this stage is rapid. In many mammalian species, particularly in humans, the interval between fertilization and implantation is exactly determined and continuous without intermission. However, European roe deer (Capreolus capreolus) embryos undergo a reversible retardation of development. This interesting reproduction strategy is called embryonic diapause (delayed implantation). After this period of embryonic arrest, development continues without further interruption. The aim of this study was to investigate embryonic development after diapause in European roe deer. Because of the embryonic diapause and the unknown date of fertilization, it was impossible to assign the embryos to a certain gestational age (days). This study describes normal stages of embryonic development mainly based on the external morphological traits of 56 well-preserved post-implantation roe deer embryos and attempts to assign the embryos to certain development stages. Carnegie stages of human embryos were used as an orientation for staging roe deer embryos. We observed a considerable range of variation of embryonic stages investigated until the end of January. We found post-implantation stages of embryonic development already at the end of December and foetuses at the end of January. Moreover, assigning the embryos to a particular stage of development allows the comparison between pairs of twins and triplets. We showed that twins and triplets were always at the same development level, despite the discrepancy in inter-twin and inter-triplet size.
胚胎发育阶段被定义为从受精开始到该阶段结束时大多数器官系统建立之间的时期。这个阶段的发育迅速。在许多哺乳动物物种中，特别是在人类中，受精和着床之间的间隔是精确确定且连续不间断的。然而，欧洲狍（Capreolus capreolus）胚胎会经历发育的可逆延迟。这种有趣的繁殖策略被称为胚胎滞育（延迟着床）。在这段胚胎停滞期之后，发育继续且不再中断。本研究的目的是调查欧洲狍滞育后的胚胎发育情况。由于胚胎滞育以及受精日期未知，无法将胚胎归为某个特定的胎龄（天数）。本研究主要基于56个保存完好的着床后狍胚胎的外部形态特征描述了胚胎发育的正常阶段，并尝试将胚胎归为特定的发育阶段。人类胚胎的卡内基分期被用作狍胚胎分期的参考。我们观察到直到1月底所研究的胚胎阶段存在相当大的变化范围。我们在12月底就发现了胚胎发育的着床后阶段，在1月底发现了胎儿。此外，将胚胎归为特定的发育阶段有助于对双胞胎和三胞胎进行比较。我们表明，尽管双胞胎和三胞胎个体之间大小存在差异，但它们总是处于相同的发育水平。
