The effects of DES before birth on the development of masculine behavior in juvenile female

Prenatal exposure to estrogen and sexual orientation in women

Studies of women exposed to high levels of estrogens prenatally could provide information regarding effects of early exposure to masculinizing hormones on sexual differentiation of brain and behavior independent of influences on the external genitalia.

1996 Study Abstract

Eight pregnant rhesus monkeys were injected with 100 microg diethylstilbestrol dipropionate (DESDP) from the 40th day of gestation until term, a long-term treatment. Male (n = 3) and female (n = 5) offspring were obtained.

The effects of diethylstilbestrol (DES) before birth on the development of masculine behavior in juvenile female rhesus monkeys, US National Library of Medicine National Institutes of Health, Hormones and behavior, NCBI PubMed PMID: 9047264, 1996 Dec.

Five other pregnant females were injected with DESDP beginning on the 115th day of gestation and continuing until either the 140th day or term–a relatively short-term treatment. Five female infants were obtained from these short-term treatments.

Monkeys from the treated pregnancies were assigned randomly to mother-infant social groups containing untreated male and female infants the same age. They were observed in their peer groups each weekday from 3 to 12 months of age, and the display of mounting and play behavior was recorded for each subject.

Results showed that DESDP significantly increased the frequency of display of these juvenile behaviors only in long-term-treated females. However, one of the aspects of mounting that is characteristic of males (the ratio of complete to abortive mounts) was unaffected even by the long-term treatment.

Thus, DESDP-treated females displayed a limited behavioral masculinization. Whether this limitation was due to dosage 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.

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