Development of the foetal membranes in the cane rat (Thryonomys swinderianus): a re-interpretation

The morphogenesis of the foetal membranes of the African cane rat (Thryonomys swinderianus, Temminck) was studied and compared with that of the caviomorphs from South America. Like the guinea pig and chinchilla, implantation in the cane rat is interstitial, amniogenesis is by cavitation, there is very early and complete inversion of yolk sac endoderm, there is a well-developed subplacenta which persists throughout gestation, and the interhaemal membrane is haemomonochorial in nature. The phylogenetic significance of these findings are discussed in the light of long geographical and temporal separation between the continents.