Essential Role of Platelet-Derived Growth Factor Receptor a in the Development of the Intraplacental Yolk Sac/Sinus of Duval in Mouse Placenta(1)
Mammalian placentas are made of two components, chorioallantoic placenta and yolk sac placenta, and although enormous diversity is found in the structure of placentas among species, all have at least one of these two components. Some marsupial species have only the yolk sac placenta, in which the yolk sac attaches to the epithelium of maternal oviduct to form the matemo-fetal transport system, whereas many mammals, including humans, only have the chorioallantoic placenta, in which the chorioallantoic tissues serve as the placenta. Rodents can be postulated to have another type of placenta, an elaborate compound of both components. levitra super active plus
The fetus of rodents is enclosed by the inverted yolk sac bilayer, which forms another materno-fetal transport system in addition to the chorioallantoic placental disc. The outer layer of the inverted yolk sac, the parietal yolk sac, faces Reichert’s membrane and may transport materials from maternal blood to the yolk sac cavity, while the inner layer, the visceral yolk sac, is vascularized abundantly by fetal blood vessels and may transport materials from the yolk sac cavity to fetal blood.
Tags: Growth Factor, Mouse Placenta, Platelet-Derived, Yolk Sac