Cytological aspects of vascular invasion by the trophoblast of Calomys callosus in hepatic tissues.
Ectoplacental cones isolated from embryos on the seventh day of pregnancy were transplanted beneath the hepatic capsule of recipient adult animals to document the morphological patterns of vascular invasion by the trophoblast in the absence of the maternal environment and the influence of its peculiar vasculature. Females, and females and males of Calomys callosus, a cricetid rodent, were used, respectively, as embryo donors and recipient animals. Three to 5 days later, the grafted regions were excised and processed for light and electron microscopy. Invasion of the liver parenchyma by the trophoblast progressed along the vascular beds, associated with gradual phagocytosis of hepatic cells, greatly favoring the morphological characterization of invasive steps exhibited by the trophoblast to access the different kinds of vessels, to trespass the various vascular components and the different levels of the surrounding hepatic parenchyma. It is possible that either in utero during the establishment of embryomaternal circulation in early pregnancy or ex utero under experimental conditions, the trophoblast exhibits similar vascular invasion behavior. In view of this, our findings may contribute to a better understanding of trophoblast cell migration to the maternal blood supply as well as the role of the trophoblast in the establishment of the placental circulation during pregnancy.
D000818:Animals; D001808:Blood Vessels / Q000502:physiology / Q000648:ultrastructure; D004624:Embryo Transfer; D005260:Female; D008099:Liver / Q000601:surgery* / Q000648:ultrastructure; D008102:Liver Circulation; D008297:Male; D012377:Rodentia; D014327:Trophoblasts / Q000502:physiology* / Q000648:ultrastructure