Relationship of decrease in fecundity with advancing age to structural changes in mouse endometrium

The aim of this study was to determine whether a relationship exists betwee n decrease in fecundity and structural changes in the antimesometrial endom etrium of the mouser Fecundity was calculated as the number of animals show ing a placental sign/number of copulated animals x 100 (%). Structural chan ges in the endometrium were examined by electron microscopy. A negative cor relation between age and fecundity was found. Fecundity was 50 % at 7 mo of age. At this age, amorphous material appeared in the region between the ba sement membrane deep to the luminal epithelium and the subepithelial cells. This material was sometimes attached to the basement membrane. It increase d in amount with advancing age, as fecundity decreased. The structure of th e uterine luminal epithelial cells did not alter with age. The results indi cated that decrease in fecundity with advancing age is correlated with the appearance of amorphous material beneath the basal lamina of the endometria l epithelium. It is suggested that this could impair communication between the luminal epithelium and the endometrial stroma, which plays an important role in implantation.