DES Effects before Birth on Masculine Behavior in Female Monkeys

DES-treated females displayed a limited behavioral masculinization, 1996


Eight pregnant rhesus monkeys were injected with 100 μg 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. 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.


  • The Effects of Diethylstilbestrol (DES) before Birth on the Development of Masculine Behavior in Juvenile Female Rhesus Monkeys, Hormones and Behavior, ScienceDirect,, December 1996.
  • Image credit come see our world.

2 Replies to “DES Effects before Birth on Masculine Behavior in Female Monkeys”

    1. I understand researchers checked what they call : (1) the display of Complete Mounts, (2) the display of routine colony breeding in which the pregnant females Abortive Mounts, (3) the performance of Rough Play, DES and Masculine Behavior of Females and (4) the display of Play Initiating actions and facial expressions.
      The whole study has 8 pages. You can access via sci-hub and paste “” in the field, then answer captcha question.

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