Sage Journals: Discover world-class research

Abstract

There are some similarities and differences in the process of sexual differentiation during development in rodents and primates. The most obvious difference is in the timing of the critical periods for morphogenesis of the reproductive tract and sexual differentiation of the central nervous system (CNS). In primates these events occur late in the first trimester while in rodents they occur in the perinatal period.

The gonadal hormones involved in morphogenesis of the male reproductive tract are identical for all mammalian species studied. Testosterone is the androgen that induces differentiation of the seminal vesicles, vas deferens, and epididymis, while dihydrotestosterone (DHT) promotes differentiation of the external genitalia, urethra, and prostate.

Estrogens, derived from aromatization of testosterone, are the proximal determinants of male sexual differentiation of the CNS in rodents. In nonhuman primates, however, a nonaromatizable androgen, DHT, produces the same effect as testosterone on sexually differentiated behaviors in female offspring. Studies of male patients with 5α-reductase deficiency have suggested that maturation of male gender identity and psychosexual behavior in humans is critically dependent on testosterone but not on normal levels of DHT in prenatal and prepubertal life. Gender identity does not appear to be unalterably fixed in humans until the time of puberty and even at this and later times environmental factors have a strong impact.

References

1. Langman, J. (1981). Medical Embryology, 4th ed. Baltimore: Williams & Wilkins, pp. 244–250.

2. Gondos, B. (1980). Development and differentiation of the testis and male reproductive tract. In: Steinberger, A. , and Steinberger, E. (eds). Testicular Development, Structure and Function, New York: Raven Press, pp. 3–20.

3. Wilson, J.D. , and Lasznitzki, I. (1971). Dihydrotestosterone formation in fetal tissues of the rabbit and rat. Endocrinology 86, 659–671.

4. Wilson, J.D. , and Siiteri, P.K. (1973). Developmental pattern of testosterone synthesis in the rabbit. Endocrinology 92, 1182–1190.

5. Siiteri, P.K. , and Wilson, J.D. (1974). Testosterone formation and metabolism during male sexual differentiation in the human embryo. J. Clin. Endocrinol. Metab. 38, 113–124.

6. Imperato-MCGINLEY, J. , Peterson, R. , and Gautier, T. (1984). Primary and secondary 5α-reductase deficiency. In: Serio, M. , Motta, M. , Zanisi, M. , and Martini, L. (eds.). Sexual Differentiation: Basic and Clinical Aspects. New York: Raven Press, pp. 233–246.

7. George, F.W. , and Peterson, K.G. (1988). 5α-dihydrotestosterone formation is necessary for embryogenesis of the rat prostate. Endocrinology 122, 1159–1164.

8. Gorski, R.A. (1986). Sexual differentiation of the brain: A model for drug-induced alterations of the reproductive system. Environ. Health Perspect. 70, 163–175.

9. Maclusky, N. , and Naftolin, F. (1981). Sexual differentiation of the central nervous system. Science 211, 1294–1303.

10.

10. Arai, Y. , Matsumoto, A. , Yamanouchi, K. , and Nishizuka, M. (1988). Perinatal sex steroid exposure, brain morphology and neuroendocrine and behavioral functions. In: Mori, T. , and Nagasawa, H. (eds.). Toxicity of Hormones in Perinatal Life. Boca Raton, FL: CRC Press, pp. 9–20.

11.

11. Leidl, W. , Braun, U. , Braun, J. , and Buck, G. (1982). The testis. In: Gass, G. , and Kaplan, H. (eds.). Handbook of Endocrinology. Boca Raton, FL: CRC Press, pp. 145–176.

12.

12. Naftolin, F. , and Maclusky, N. (1984). Aromatization hypothesis revisited. In: Serio, M. , Motta, M. , Zanisi, M. , and Martini, L. (eds.). Sexual Differentiation: Basic and Clinical Aspects. New York: Raven Press, pp. 79–92.

13.

13. Goy, R. , Uno, H. , and Sholl, S. (1988). Psychological and anatomical consequences of prenatal exposure to androgens in female rhesus. In: Mori, T. , and Nagasawa, H. (eds.). Toxicity of Hormones in Perinatal Life Boca Raton, FL: CRC Press, pp. 9–20.

14.

14. Goy, R. , and Resko, J. (1972). Gonadal hormones and behavior of normal and pseudohermaphroditic nonhuman female primates. Recent Prog. Horm. Res. 28, 707–721.

15.

15. Resko, J. , Ellinwood, W. (1984). Sexual differentiation in the brain of primates. In: Serio, M. , Motta, M. , Zanisi, M. , and Martini, L. (eds.). Sexual Differentiation: Basic and Clinical Aspects. New York: Raven Press, pp. 169–182.

Sexual Differentiation in the Neonate: Rodent vs. Primate Comparisons

Abstract

References