Ovarian defect in rats carrying the growth and reproduction complex

The growth and reproduction complex contains recessive genes (grc) which influence body weight and gonadal development. Homozygous males are sterile, and they have an arrest of spermatogenesis at the primary spermatocyte stage. Homozygous females are fertile but have a reduced reproductive capacity. The data presented in this paper show that the latter defect is associated with a decrease in the relative number of secondary ovarian follicles and an increase in the number of atretic follicles. This finding indicates that most of the primary follicles do not mature properly. Thus, the genetic defect in gametogenesis controlled by the grc appears to occur at the same stage of development in both females and males.