Department of Anatomy, Juntendo University School of Medicine, Hongo, Tokyo 113, Japan
(Received 18 October 1977)
Differentiation of sexual behaviour patterns in male rats is dependent on the internal secretion of the testes during neonatal life. Removal of the testes at this time causes feminization and results in male rats which display female patterns of sexual behaviour (Gorski, 1971). Female patterns of behaviour are usually rare in normal male rats but recently we found that transection of the dorsal afferent neurones to the preoptic and anterior hypothalamic areas potentiated the display of lordosis in hormonally primed male rats (Yamanouchi & Arai, 1975). In the present study, further neuroanatomical analysis was carried out to clarify the localization of the afferent pathway involved in the regulation of lordosis behaviour.
Anterior or posterior roof deafferentation (ARD or PRD) was performed by lowering an L-shaped Halasz knife (2-5 mm horizontal blade) to the level