Effects of intracranial implantation of oestradiol and dihydrotestosterone on the sexual behaviour of the lizard Anolis carolinensis.

Intrahypothalamic implantation of oestradiol and dihydrotestosterone rapidly restored sexual behaviour in castrated, sexually inactive Anolis carolinensis. Implants in areas other than the anterior hypothalamus-preoptic area failed to elicit sexual behaviour. Male aggressive behaviour was unaffected by intracranial hormone implants. Histological examination of the renal sex segment, a secondary sex structure, gave no indication of leakage into the peripheral plasma. The effectiveness of oestradiol and dihydrotestosterone in inducing male courtship behaviour when administered intracranially was compared with the relative ineffectiveness of systemic injections of these hormones.