Figure 6
From: Chorioallantoic placentation in Galea spixii (Rodentia, Caviomorpha, Caviidae)
The parietal yolk sac. (A) Early pregnancy, PAS, counterstained with HE. The cytotrophoblast below the parietal yolk sac (pys) and the Reichert's membrane (rm) contains glycogen or related substances and may be active in secretion. Below is the trophospongium with its zone of proliferating trophoblast cells (ct) and the maternal blood channels (mbc). (B) Near term, TEM. The parietal yolk sac is still multilayered. It possesses apical microvilli, electron-dense inclusions and large intracellular spaces. Scale bars = 0.1 mm for histology and 2 μm for TEM.