OBSERVATIONS ON THE CHORIOALLANTOIC PLACENTA OF THE INDIAN FLYING FOX, PTEROPUS-GIGANTEUS-GIGANTEUS

The present study was undertaken to resolve (1) whether the interhaema l membrane of Pteropus giganteus at term is endotheliochorial or haemo chorial and (2) how the trophoblast is layered. Females carrying late limb bud stage (CRL 12.95 mm) and advanced fetus (CRL 26.95 mm) were c ollected at Nagpur, India. The placenta in late limb bud stage was exa mined by light microscopy and that of advanced pregnancy by both light and electron microscopy. Our observations reveal that the chorioallan toic placenta at late limb bud stage is horse-shoe shaped and endothel iodichorial while that of advanced pregnancy is mesometrial, labyrinth ine, and discoidal and shows a tendency toward becoming haemochorial. The junctional zone contained multinucleate giant cells. Detached endo thelial cells were observed in the maternal capillary lumen during the advanced stage. Under light microscope a thick homogeneous layer was noticed deeper to the endothelial cells and in the regions devoid of s uch cells. A PAS-positive, highly reticulate and discontinuous interst itial membrane was noticed embedded in the thickness of the homogeneou s layer. The ultrastructure of the interhaemal membrane of the chorioa llantoic placenta in advanced pregnancy shows a tendency from endothel iodichorial to haemodichorial condition. The Pteropus interhaemal memb rane is compared with that of bats of other families. The earlier conc lusion that the maternal endothelium is typically different for primit ive and extant families is denied on the basis of comparative ultrastr ucture.