THE EFFECTS OF DIETHYLSTILBESTROL (DES) BEFORE BIRTH ON THE DEVELOPMENT OF MASCULINE BEHAVIOR IN JUVENILE FEMALE RHESUS-MONKEYS

Eight pregnant rhesus monkeys were injected with 100 mu g diethylstilb estrol dipropionate (DESDP) from the 40th day of gestation until term, a long-term treatment. Male (n = 3) and female (n = 5) offspring were obtained. Five other pregnant females were injected with DESDP beginn ing on the 115th day of gestation and continuing until either the 140t h day or term-a relatively short-term treatment. Five female infants w ere obtained from these short-term treatments. Monkeys from the treate d pregnancies were assigned randomly to mother-infant social groups co ntaining untreated male and female infants the same age. They were obs erved in their peer groups each weekday from 3 to 12 months of age, an d the display of mounting and play behavior was recorded for each subj ect. Results showed that DESDP significantly increased the frequency o f display of these juvenile behaviors only in long-term-treated female s. However, one of the aspects of mounting that is characteristic of m ales (the ratio of complete to abortive mounts) was unaffected even by the long-term treatment. Thus, DESDP-treated females displayed a limi ted behavioral masculinization. Whether this limitation was due to dos age and/or timing or to a selective action of DESDP was not determined . DESDP-treated males were not altered in any measurable way compared to untreated males. (C) 1996 Academic Press.