Oestrous cycle in septal rat females

Bilateral lesions of the dorsal part of the septal area were produced in the brain of female rats of Wistar and Long-Evans stocks. The cytogram of their vaginal smears was evaluated repeatedly from the 30th day after surgery and permanent impairment of their oestrous cycle was found. In comparison with intact control females, oestrous phases were detected more frequently whereas dioestrous phases were observed less frequently. The proportions between the individual periods of the oestrous phase (i.e. pro-oestrus, oestrus and metoestrus) were equal in both septal and intact animals. No difference was found between the rat stocks used. Similarly, the previous life history of the rats which had been housed either in a socially impoverished environment (i.e. single cages) or in large communities (colonies) exerted no influence upon the postoperative impairment of the oestrous cycle.