Effects of cerebral lesions, blinding, and domestication on gonadal functions of the female ferret.

Abstract

SUMMARY Lesions in the anterior part of the hypothalamus may hasten the onset of the annual breeding season of the female ferret, without affecting fertility. An early onset of oestrus was also noted in one ferret with a lesion that had been blinded by removal of the eyes. Four other doubly-operated ferrets remained anoestrous during the observation period; they had become markedly obese and displayed hyperphagia. Removal of the frontal parts of the brain was not followed by early onset of oestrus, and did not interfere with fertility or with normal thyroid gland activity. Ferrets kept in the laboratory (illuminated by artificial light only, and for 8 hr. per day) for more than 1 year—here designated as domesticated ferrets—develop an abnormal pattern of oestrous rhythm. Second and subsequent oestrous periods usually begin in the late autumn or early winter, and occurred with an interval of nearly 2 years in two ferrets followed for 3½ years. It is demonstrated that the inclusion of such ferrets in an experiment designed to note effects of an experimental procedure upon the time of onset of oestrus is not justified.