Evaluation of the involvement of the adrenals in the pheromonal influences on the oestrous cycle of laboratory mice.

Unisexual grouping of female mice induced irregularities in their oestrous cycles. However, no significant difference in body weight and in the weights of adrenals, uteri and ovaries and in the adrenal delta 5 3 beta-hydroxysteroid dehydrogenase (HSD) activity was found between unisexually grouped females and individually housed females. Adrenalectomy of females failed to prevent the oestrous cycle irregularities induced by unisexual grouping. Furthermore, adrenalectomized females in unisexual groups responded to exposure to males by exhibiting oestrus acceleration and synchronization (the Whitten effect). The results rule out the involvement of the adrenals in the oestrous cycle irregularities induced by unisexual grouping and in the induction of the Whitten effect in unisexually grouped females.