Dogmas and unsolved problems in brain sex differentiation

Dogmas and unsolved problems in brain sex differentiation
Ingrid Reisert and Christof Pilgrim ( Germany )

Throughout the anima l kingdom, nervous systems dif- fer between sexes. Sexual dimorphisms in neuroanatomical, physiological, and neurochemical parameters are reflected by sex-specific forms of behavior, in particular with regard to reproduction, and sex differences in neuroendocrine regula- tion. The present volume of Biomedical Reviews is mainly concerned with sex differences in the mammalian and human brain. However, it should at least be mentioned that the most convincing correlations between neuroanatomical and behav-ioral data have been provided by studies of the sexual differ-entiation of song control systems in bird species, in which the males sing and the females do not. In mammals, research used to locus on the hypothalamus commonly seen as the center for control of reproductive behavior and integration of hormonal and neural responses of the organism. We have therefore asked A Mafsumofo and %. /*ra/ to review the evidence for the hy- pothesis that sexually dimorphic functions of the hypothala- mus are indeed based on a sex-specific neural circuitry. Not- withstanding the central role of the hypothalamus, it is impor- tant to note that more and more, often subtle, anatomical and/or functional sex differences have been and continue to be de- tected in other areas of the central nervous system. Of particu- lar interest are sex differences in neural systems than are known
Reviews 1997; 7: 1-3
Received for publication 17 April 1997 and accepted 8 June 1997

Correspondence and reprint requests to Dr Ingrid Reisert, Analomie und Zellbiologie. Universitat Ulm, D-89069 Ulm, Germany. Tel: 49 (731) 502 3226, Pax: 49 (731) 502 3217

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