Histological studies on the vaginal plate and vaginal epithelium in androgenized rats

Summary The present work is a histological study on the epithelium of the vaginal plate and vagina proper of intact rats, 5–45 days old, and of rats which were injected with 1.5 mg testosterone propionate at the age of 5 days (androgenized) and studied at different ages from 6–45 days. Moreover, the vaginal epithelium in adult androgenized rats was studied.A perforation of the vaginal plate and an external orifice of the vagina was seen in intact rats about 35 days old. The perforation resulted from cornification in scattered, later confluencing, regions in the epithelium of the plate.The androgenized rats developed a precocious vaginal opening at 12 days of age. Also in these animals the perforation of the plate resulted from a cornification in the center of the strongly thickened plate. After a lumen had developed the plate region presented a transitional epithelium. This was transformed into a stratified squamous epithelium at about 35–45 days, that is when the first oestrus occurred in intact controls. In contrast to the strong reaction to testosterone in the epithelium of the vaginal plate no effects could be seen in the vaginal epithelium proper, with the exception of some leucocytic infiltration.The adult androgenized rats had a cornified vaginal epithelium which in two cases showed some leucocytic infiltration. Acknowledgement. This investigation was supported by grants from the Swedish Medical Research Council (no 14X-571-02 and no Y 479) and from the Swedish Cancer Society (no 64164).