Effect of surgical disconnection of the medial basal hypothalamus on postcoital reflex ovulation in the rabbit.

The effects of hypothalamic transections of varying lengths on reflex ovulation in the rabbit are reported. Circular cuts which surgically isolated the medial basal hypothalamus (MBH) from the remainder of the brain did not prevent copulation 4 to 24 h later, but did block reflex ovulation. On the contrary, hemicircular cuts of either the rostral, caudal or one lateral haf of the circular cut did not prevent reflex ovulation. These results suggest that coital stimuli reach the MBH through a diffuse network of fibers and that only very extensive deaferrentation of the MBH can cause blockade of ovulation in rabbits. These data are compared with results of other investigators in which anterior deafferentation of the MBH blocked reflex and spontaneous ovulation in rats.