Induction of Ossification in the Clitoris of Neonatal Female Rats by Administration of Androgens

The effects of a single injection of sex steroids in neonatal female Sprague-Dawley rats on the development of os clitoris were studied. Os clitoris was not detected in neonatally intact control female rats at 28 days of age but was seen in 100% of neonatally androgen-injected ovariectomized or nonovariectomized rats at 28 days of age. Testosterone propionate (1 mg) or 5a-dihydrotestosterone (1 mg) was injected sc within 24 h after birth. On the contrary, single injections of progesterone (1 mg) and 17β-estradiol (0.1 mg) in female rats had no effects. Histological studies of the clitoris in female rats treated with testosterone propionate revealed the aggregation of immature stromal cells at 3 days of age, the appearance of homogenous eosinophilic interstitial substance in the intercellular spaces at 7 days of age, the development of hyalin cartilage at 14 days of age, and the formation of bone with cavity at 21 days of age. These results indicate that the initiation of bone formation in the clitoris is ...