We do not have a clear idea of the functional significance of these structural
sex differences. Some of these structures, such as the interstitial nucleus of
the anterior hypothalamus, are located in an area of the brain known to play a
role in the regulation of reproductive behavior. Sex differences in the corpus
callosum and perhaps the anterior commissure could be related to
interhemispheric communication. In human beings, brain function is more
lateralized in males. However, even in laboratory animals, the specific
functions of the various sexually dimorphic nuclei are not clear.
Of considerable interest are 3 recent reports of a structural brain difference
between homosexual and apparently heterosexual men. One component of the
interstitial nucleus of the anterior hypothalamus is larger in heterosexual
men. In addition, the suprachiasmatic nucleus of homosexual men is larger than
that of either heterosexual


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