No abstract

Male deer mice (Peromyscus maniculatus), born of mothers housed on a longday (LD) photoperiod (15:9 hr light/dark), were either switched to a short-day (SD) photoperiod (6:18 hr) at birth or continued on their prenatal LD photoperiod. From weaning until 6 wk of age, the males were housed either in cohabitation with an adult female or in social isolation. Males reared on an SD photoperiod had smaller testes, seminal vesicles, and ventral sebaceous glands than did males reared on LD. Postweaning exposure of SD males to females stimulated reproductive organ growth as measured at 6 wk of age. Both photic and social stimuli regulate reproductive development in male deer mice. Positive social cues can stimulate maturation even in the presence of negative photic cues.

No abstract

No abstract

Female hamsters were treated with oil, 3-/ig., 30-/ig., or 300-yug. testosterone propionate (TP) as neonates. Neonatal TP treatment delayed the onset of puberty by 4.5 days to an age near that previously reported for the male hamster. In addition, neonatal TP altered genital morphology, induced the capacity for mounting behavior, and at the highest dosage, disrupted the ability to bear and rear young. Vaginal and behavioral estrous cycles, however, were not influenced by neonatal TP. In a second experiment, 600-/*g. TP administered neonatally blocked estrous cyclicity, but did not eliminate the capacity to display feminine sexual behavior. These results imply that "mascuhnization" and "defeminization" are separate aspects of neurobehavioral sexual differentiation, and that "defeminization" includes several independent physiological processes.