Alberto Míryan L V, Meirelles Flavio V, Perecin Felipe, Ambrósio Carlos E, Favaron Phelipe O, Franciolli André L R, Mess Andrea M, Dos Santos José M, Rici Rose E G, Bertolini Marcelo, Miglino Maria A
Department of Surgery, School of Veterinary Medicine and Animal Science, University of Sao Paulo, Av. Prof. Orlando Marques de Paiva, 87, Butantã, 05508-270, Sao Paulo, Brazil.
Reprod Fertil Dev. 2013;25(6):907-17. doi: 10.1071/RD12092.
Assisted reproduction techniques have improved agricultural breeding in the bovine. However, important development steps may differ from the situation in vivo and there is a high mortality rate during the first trimester of gestation. To better understand these events, we investigated the development of embryos and fetal membranes following fixed-time AI (FTAI), IVF and nuclear transfer (NT). The onset of yolk-sac development was not normal in cloned embryos. Later steps differed from conditions in vivo in all three groups; the yolk-sac was yellowish and juxtaposed with the amniotic membrane. Vascularisation of the chorioallantoic membrane was relatively late and low in NT gestations, but normal in the others. The overall development of the embryos was normal, as indicated by morphology and regression analysis of growth rate. However, NT conceptuses were significantly smaller, with the livers in some embryos occupying the abdominal cavity and others exhibiting heart abnormalities. In conclusion, the yolk-sac and the cardiovascular system seem to be vulnerable to morphogenetic alterations. Future studies will focus on gene expression and early vascularisation processes to investigate whether these changes may be responsible for the high incidence of intrauterine mortality, especially in clones.
辅助生殖技术已改善了牛的农业育种。然而，重要的发育步骤可能与体内情况不同，并且在妊娠的前三个月死亡率很高。为了更好地理解这些情况，我们研究了定时人工授精（FTAI）、体外受精（IVF）和核移植（NT）后胚胎和胎膜的发育情况。克隆胚胎中卵黄囊发育的起始不正常。在所有三组中，后续步骤均与体内情况不同；卵黄囊呈淡黄色并与羊膜并列。在核移植妊娠中，绒毛膜尿囊膜的血管化相对较晚且程度较低，但在其他组中正常。从形态学和生长速率回归分析来看，胚胎的整体发育是正常的。然而，核移植胚胎显著较小，一些胚胎的肝脏占据腹腔，另一些则表现出心脏异常。总之，卵黄囊和心血管系统似乎易受形态发生改变的影响。未来的研究将集中在基因表达和早期血管化过程，以调查这些变化是否可能是宫内死亡率高的原因，尤其是在克隆胚胎中。
