Changes in germ cells population and in vitro oocyte maturation in female mice with imperforated vagina.

This study characterized female mice with a congenital defect in their reproductive tract. In females derived from an outbred colony maintained in the Department of Genetics and Evolution, the frequency of the imperforated vaginae was approximately 2%. A consequence of this defect is infertility. Affected animals developed hydrometrocolpos (the uterus and vagina were greatly distended by fluid). Morphology of the ovary and oviduct was normal and similar to that of control mice. In the females with an imperforated vagina numerous corpora lutea were observed. Accordingly, we have found that both spontaneous as well as exogenous gonadotrophin-induced ovulation occurs in such females. Nevertheless, oocytes derived from ovaries of occluded females exhibited a partial block during in vitro maturation. Histological analysis of ovarian tissue revealed an increase in the number of primary follicles (type I follicles) and a decrease in the number of secondary and antral follicles (type IV and type VI follicles) when compared with control mice. The concentration of androgens in the ovarian tissue was higher in the affected females. Our data show that females with an imperforated vagina can be a useful model for studying the mechanism of genetic control of the development of the urogenital tract in mammals.