School of Veterinary Science, National University of La Plata, Argentina.
Placenta. 2011 Dec;32(12):963-8. doi: 10.1016/j.placenta.2011.09.002. Epub 2011 Oct 6.
Reproduction in the plains viscacha is characterized by the polyovulation of hundreds of oocytes, the loss of implantation and the development of 1-3 offspring. Our goal was to determine whether placental development was affected by these specializations.
Thirteen placentas from early pregnancy to near-term pregnancy were analyzed using histological, immunohistochemical and transmission electron microscopy.
An inverted, villous yolk sac was present. Placentas were formed by the trophospongium, labyrinth and subplacenta. A lobulated structure with a hemomonochorial barrier was established early in pregnancy. Proliferating trophoblast that was clustered at the outer border and inside the labyrinth was responsible for placental growth. Trophoblast invasion resulted from the cellular trophoblast and syncytial streamers derived from the subplacenta. Different from other caviomorphs, numerous giant cells were observed.
The principle processes of placentation in caviomorphs follow an extraordinarily stable pattern that is independent of specializations, such as polyovulation.
平原旱獭的繁殖特征是数百个卵母细胞的多排卵、着床失败和 1-3 个后代的发育。我们的目标是确定胎盘发育是否受到这些特化的影响。
使用组织学、免疫组织化学和透射电子显微镜分析了 13 例从早孕到近足月的胎盘。
存在倒置的绒毛卵黄囊。胎盘由滋养层海绵体、胎盘和子胎盘组成。在妊娠早期建立了具有血单绒毛膜屏障的分叶状结构。位于胎盘外边界和胎盘内部的簇状增殖滋养细胞负责胎盘生长。滋养细胞浸润是由子胎盘衍生的细胞滋养细胞和合体滋养细胞流引起的。与其他啮齿动物不同，观察到大量的巨细胞。
在与多排卵等特化无关的情况下，啮齿动物胎盘形成的主要过程遵循一种非常稳定的模式。
