Influence of Compensatory Mechanisms and the Pineal Gland on Dark-induced Gonadal Atrophy in Male Hamsters

Abstract

IT has been postulated that the gonads of male and female hamsters regress to a non-functional state as a normal seasonal response to short days and low temperatures in the autumn and winter¹. Under laboratory conditions, the same results follow exposures to short photo-periods^1–3. The functional change in the gonads is evidently controlled by the pineal gland, which itself responds to changing light periods, since pinealectomized animals show no regression of gonads when they are exposed to short photoperiods. A variable hypertrophic response of one gonad is a result of excision of the other. There are, therefore, probable hormonal processes which exert effects on the gonads opposite to those exerted by the pineal gland. In the course of our work, there arose a question as to whether the depressant action of the pineal gland could be counteracted by the compensatory process which follows unilateral castration. The following experiments were designed to elicit an answer to this question.