Placenta extrachorialis in the stumptailed macaque (Macaca arctoides)

Placenta extrachorialis was diagnosed in two of 56 placentas obtained from stumtailed macaques (Macaca arctoides) after elective cesarean section. The condition was characterized by the presence of an annular ring of necrotic tissue and fibrin at the margin of the villous chorion. Because these cases occurred in two of six known primiparous females, it was suggested that thte condition may account, at least in part, for the high incidence of pregnancy-related problems observed in primiparous stumptailed macaques.