The histology and Fine Structure of the reproductive organs fetal membranes and placenta of the East African Springhare (Pedetes Capensis Larvalis Hollister)

Abstract

The East African springhare (Pedetes capensis larvalis Hollister) used in this study were collected from Machakos and Kiambu districs. The gonadogenital organs and fetal membranes were fixed and examined by routine histological, histochemical and ultrastructural methods. 'The springhare has a duplicated uterus, large muscular, and aglandular cervix and a nonduplicated vagina. It ovulates only one egg at a time leading to a single embryo. The implan~ation is superficial and mesometrial. The embryonic disc is mesometrially oriented. A massive preplacenta is evident before the chorio-allantoic placenta is formed. The parietal trophoblast persists throughout pregnancy and, with the advance in gestation, proliferates and fuses with the uterine wall in many areas. No inversion of the germ layers occurs 1n the East African springhare; this contrasts with the inversion of the germ layers seen in the South African springhare and in most rodents as reported 1n the literature. The placental barrier is essentially endotheliochorial, consisting of maternal capillary endothelium with a prominent acidophilic PAS-positive basal lamina and a layer of syncytial trophoblast; a situation which is similar to that found in the kangaroo rat (a sciuromorph). The demonstration of the endotheliochorial type of placenta by ultrastructural method confirms the previous observation by Mossman (1957). There is no subplacenta in the East African springhare. The decidual reaction involves mostly stromal cells and no giant cells are evident. Most of the decidua is destroyed by mid-term. This study clearly demonstrates a close similarity of the springhare to the rest of the rodents in gonadogenital/ placental structures and fetal membranes. In particular the East African springhare is virtually identical to the South African variety. It is also very closely related to the kangaroo rat. Based on the fetal membranes and placental structures, the East African springhare is more closely related to the sciuromorphs than the myomorphs or hystricomorphs in which it has been previously classified. It is therefore concluded that the springhare should be placed in its own superfamily of Pedetoidea in the suborder Sciuromorpha.