Ultrastructural differentiation of stromal and vascular components in early macaque placental villi.

摘要: In this study, closely staged placental villi from rhesus monkeys between 19 and 60 days of gestation were used to examine (1) the origin endothelial cells mechanism angiogenesis in villi; (2) macrophages (Hofbauer cells), (3) reticular that compartmentalize stroma. The results did not support concept early stromal derived by situ delamination cytotrophoblast. extraembryonic mesodermal (mesenchymal) at earliest ages examined contained considerable granular ER. These organized into groups formed primitive intercellular junctions, thus giving rise angioblastic masses. masses cellular, syncytial; lumen formation was result intracellular vacuolization, but rather acquisition junctionally defined spaces. capillaries lacked intravascular blood a basal lamina. Later, evident lumina. At about 45–50 gestation, fetal began indent surface trophoblast. lamina still had developed gestation. Between 35 40 significant morphological changes took place villous Evidence obtained mesenchymal differentiated subdivided stroma fibrilrich fibril-free compartments. same time, Hofbauer observed for first time; they occupied regions We observe any clear indications intermediate stages differentiation other cell types cells. It is suggested may have an independent types; one possibility are monocytes as tissues. further activities be important remodeling extracellular matrix related process branching morphogenesis villi.