ANDROGENS AND MASCULINIZATION OF GENITALIA IN THE SPOTTED HYENA (CROCUTA-CROCUTA) - 3 - EFFECTS OF JUVENILE GONADECTOMY

Studies involving the administration of anti-androgens to spotted hyae nas during fetal development have raised questions concerning the prec ise contributions of steroids to phallic growth in these animals. If, gonadal androgens promote postnatal penile growth in males, the follow ing would be expected: (a) a period of accelerated growth accompanying achievement of puberty, and (b) a marked reduction in adult penile si ze and density of penile spines after gonadectomy. if a similar androg enic pubertal process stimulates clitoral growth in these highly 'masc ulinized' hyaenas, parallel observations in females would be expected; however, the role of oestrogens in accounting for female-typical clit oral development would also have to be considered. The results of the present study suggest a limited role, if any, for androgenic stimulati on of phallic growth. That is, penile growth was greater during the 10 month period preceding puberty, than during an 18-month period that i ncluded the traditional increase in pubertal androgens. In addition, p re-pubertal castration had minimal effects on penile length, diameter, or the presence of penile spines. In females, most clitoral growth al so occurred before puberty, although pre-pubertal ovariectomy produced significant reductions in clitoral diameter and the elasticity of the urogenital meatus. These feminine characteristics, which normally dis tinguish the female from the male phallus in this species, were partia lly restored by a brief period of oestrogen administration. Both sexes displayed erections many years after pre-pubertal castration. The res ults of the present study suggest that postnatal phallic growth is lar gely independent of gonadal steroids, with oestrogenic facilitation of female-typical clitoral characteristics in spotted hyaenas.