Histology of the chorioallantoic placenta of the golden-rumped elephant shrew (Rhynchocyon chrysopygus Gunther, 1881).

The chorioallantoic placenta of the golden-rumped elephant shrew, Rhynchocyon chrysopygus has been studied. The implantation is eccentric and mesometrial. The placenta is haemochorial and is divisible into 4 zones namely columnar, proliferative, spongy and basal trophoblastic zones. The proliferative zone, which is peculiar to the Macroscelididae, is present in the early and mid pregnancy but disappears in later stages. The presence of the basal trophoblastic zone, the absence of a true zone of degeneration, the absence of the "mesoplacentarium" (of Starck 1949) and the structure of the wall of the allantoic vessels differentiate Rhynchocyon from other elephant shrews that have been studied. The presence of large cells in the maternal blood spaces and in the lumen of decidual vessels is also reported but the fate of such cells is not yet known.