EFFECT OF NEONATAL TREATMENT OF MALE MICE WITH ANTIANDROGENS AND OF FEMALES WITH ANDROGENS ON DEVELOPMENT OF OS PENIS AND OS CLITORIDIS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 121  (APR) , 363-370
Abstract
The fetal and postnatal development of the os penis and os clitoridis in ICR mice and the effect of neonatal treatment of males with antiandrogens and females with androgens were studied histologically and by radiography. In mice of either sex a dense mesenchymatous formation ventral to the urethra appears in the late fetal period and represents the anlage for the bones of the external genitalia. The os penis consists of a proximal part which develops as intramembranous bone in the outer region and as endochondral bone at the base of the anlage. The distal part is formed later as a cartilaginous rod which subsequently ossifies. In females a minute focus of ossification arises in the early postnatal period and grows into the minute os clitoridis which is analogous to the proximal intramembranous bone of the os penis. Treatment of males with cyproterone acetate during the first 4 days after birth (daily dose: 100 .mu.g in 0.02 ml of sesame oil) inhibits growth and delays calcification of the os penis. Neonatal castration has an even greater inhibitory effect. Treatment of females with testosterone or dihydrotestosterone during the first 2 postnatal days (daily dose: 300 .mu.g in 0.02 ml of sesame oil) promotes the growth of the proximal bony rod of the os clitoridis, but induces merely a rudimentary collagenous distal element. The clitoris in female mice, unlike that in female rats, does not respond with chondrogenesis to androgenic treatment even in the neonatal period. Neonatal application of .beta.-estradiol to females does not affect the formation of growth of the os clitoridis.