Late fetal development and selective resorption in Saccostomus campestris (cricetidae)

Abstract

When female Saccostomus campestris are stressed during pregnancy they may resorb part of the litter. Resorption can take place on more than one occasion during the same pregnancy without affecting the development of the rest of the litter. The last resorption may be initiated as late as 72-48 h before parturition. No other rodents with a similar gestation appear to resorb at this stage. Resorbing fetuses are isolated within uterine compartments from viable fetuses. Ossification occurs at a comparatively late stage of pregnancy in Saccostomus campestris, and there is a lag-period in fetal growth exactly 72-48 h before parturition. These factors may facilitate late resorption in this species. Factors that may cause stress in this species are most likely environmental; in the present study, dipping of the animal colony to treat for a mite infestation may have induced resorption in some of the females.