Roslyn Holly Fitch (1995) Estrogen is Still Important. Psycoloquy: 6(42) Sex Brain (8)

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PSYCOLOQUY (ISSN 1055-0143) is sponsored by the American Psychological Association (APA).
Psycoloquy 6(42): Estrogen is Still Important

Reply to McCarthy on Sex-Brain

Roslyn Holly Fitch
Center for Molecular and Behavioral Neuroscience
Rutgers University
197 University Ave.
Newark, NJ 07102

Victor H. Denenberg
Biobehavioral Sciences Graduate Degree Program
University of Connecticut
Storrs, CT 06269-4154


McCarthy (1995) provides an excellent review of less known, but potential feminizing agents, and asserts that this area of research should not focus on estrogen to the exclusion of other factors. We agree, but also reiterate that data show specific and significant feminizing effects of estrogen. Such findings argue that although estrogen may not be the sole feminizing influence, it is nevertheless a critical one.


corpus callosum, development, estrogen, feminization, ovaries, sensitive period.
1. We find little to add to McCarthy's excellent review of factors other than ovarian estrogen, and other than ovarian steroids, which may be involved in female differentiation (McCarthy, 1995). We would only call attention to a number of studies in which the ovaries have been removed, and estrogen replacement provided, with comparison against untreated Ovx subjects (e.g., Frankfurt et al., 1990; Mack et al., 1993; Pappas et al., 1979; Stewart & Cygan, 1980). By directly addressing the effects of presence or absence of estrogen, rather than the ovaries per se, such findings specifically lend support to a critical role for estrogen in the feminization process. Nevertheless, such evidence should not preclude investigation of other factors, as reviewed by McCarthy, which may also play an important role in female development and sexual differentiation. As has been noted by other commentators, it seems likely that feminization, and indeed sexual differentiation in general, reflect highly complex interactions between intrinsic and extrinsic factors and a dynamic system.


Fitch, R.H. & Denenberg, V. (1995) A Role For Ovarian Hormones In Sexual Differentiation of the Brain. PSYCOLOQUY 6(5) sex-brain.1.fitch.

Frankfurt, M., Gould, E., Woolley, C. S. & McEwen, B.S. (1990) Gonadal steroids modify dendritic spine density in ventromedial hypothalamic neurons: a golgi study in the adult rat. Neuroendocrinology 51: 530-535.

Mack, C.M., Fitch, R.H., Cowell, P.E., Schrott, L.M. & Denenberg, V.H. (1993) Ovarian estrogen acts to feminize the rat's corpus callosum. Developmental Brain Research 71: 115-119.

McCarthy, M. (1995) How About Sexually Differentiating Factors Other Than Estrogen? PSYCOLOQUY 6(32) sex-brain.7.mccarthy.

Pappas, C.T.E., Diamond, M.C. & Johnson, R.E. (1979) Morphological changes in the cerebral cortex of rats with altered levels of ovarian hormones. Behavioral and Neural Biology 26: 298-310.

Stewart, J. & Cygan, D. (1980) Ovarian hormones act early in development to feminize open field behavior in the rat. Hormones and Behavior 14: 20-32.

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