Abstract
Pregnant female ICR/Swiss mice were injected with 6 mg of cyproterone acetate (CA) from days 14 to 20 of pregnancy. Offsprings were delivered on day 20 of pregnancy by Caesarian section and castrated at the same time under cold anesthesia. Then, animals were foster-nursed by other lactating females. Feminized male offsprings were divided into 3 groups and treated once daily for the first 10 days of life with sesame oil (Group 1), 20 μg estradiol-17 β (ED) (Group 2) and 50 μg ED (Group 3), respectively. The animals were sacrificed at 60 days of age. Histological examination showed that a vagina which anteriorly ended blindly developed in all feminized male mice. In most of these feminized males, insufficient development of urethrovaginal septum was noted. However, the separation of the urogenital sinus into the ventral urinary tract and the dorsal vagina was easily identified by their histological appearances. In oil-injected controls (Group 1), the vaginal epithelium consisted of 2-4 cell layers and exhibited the stratified squamous and/or cuboidal structures, but there was no sign of cornification. In contrast, the vaginal eqithelium of estrogenized feminized males showed long-lasting hyperplasia after the withdrawal of exogenous estrogen. In 2 out of 15 feminized males of Group 3, well-differentiated squamous stratification and intensive cornification were found from the anterior to posterior parts of the vaginal epithelium. In most of the rest animals, cornification was found limited to the middle and posterior parts of the vagina, although hyperplasia of the vaginal eqithelium (7-8 cell layers) was consistently observed throughout all parts of the vagina. Since the most parts of the vaginal anlage of CA-induced feminized males in thought to be originated from the urogenital sinus epithelium, persistent cornification in the middle and posterior parts of the vagina observed in the present study may indicate the possible contribution of sinus-orginated epithelial cells to “estrogen independent vaginal cornification'”.
