Sexual differentiation of play behavior in the ferret.
Three experiments were performed to elucidate the endocrine mechanisms responsible for sex differences in the prepubertal play behavior of ferrets. In Experiment 1, gonadally intact adolescent males exhibited higher levels of "stand-over" behavior than females did in tests between 63 and 123 days of age with gonadally intact female partners of the same age. In Experiment 2, ferrets exposed to androgen or to ovarian steroids over Days 5-20 of postnatal life subsequently exhibited significantly higher levels of stand-over behavior in tests with female partners than did control females gonadectomized on Day 5 and not subsequently given any steroids. However, none of the subjects in Experiment 2 exhibited levels of stand-over behavior comparable to those of the gonadally intact males in Experiment 1. In Experiment 3, males gonadectomized and implanted subcutaneously with testosterone capsules on Day 70 and tested with female partners at 84-96 days of age exhibited levels of stand-over behavior comparable to those observed in Experiment 1 in gonadally intact males of the same age (Weeks 12-14). Males gonadectomized on Day 70 and given no hormone at the time of testing exhibited significantly lower levels of this behavior. Significantly lower levels of this behavior were also exhibited by males gonadectomized on Day 35 and females gonadectomized on Day 70 regardless of whether they were tested with testosterone present after Day 70. Sex differences in the expression of prepubertal play behavior of ferrets apparently result from differential exposure of males and females to androgen over an extended postnatal period.