THE LOCALIZATION IN THE BRAIN STEM OF THE OESTROUS RESPONSES OF THE FEMALE GUINEA PIG

Abstract

Typical oestrous responses were obtained from ovariectomized guinea pigs injected with.suitable hormone preps. after destruction of all brain tissue rostral to a plane extending from the ant. margin of the superior colliculi to the ant. margin of the mammillary bodies. These responses were abolished by a further tran-section from the same level dorsally to a point just behind the mammillary bodies. Evidence indicated that the afferent pathways involved in this response run through the post. quadrants of the cord, cross in the medulla and extend through the optic tectum. The same stimulus, namely, light stroking of the hair of the back and rump, which evoked sexual behavior in the ? guinea pig during oestrus, elicited evading response (squeaking, kicking, running away, etc.) during dioestrus. The evading responses were lost following the same lesions of the spinal cord and tectum which abolished the oestrous responses.