Oestrus suppression in wild mice: source of pheromonal cue.

Regularly cycling female mice attained anoestrus when they were exposed to voided urine or to urine directly collected from the bladder of intact females. In contrast, the urine of spayed females or the clitoral gland homogenate from intact females was found ineffective in suppressing oestrus. The findings thus clearly elucidate the presence of an oestrous-suppressing pheromone in the urine of intact females whether voided or collected directly from the bladder and confirm the oestrogen dependence of the pheromone. Clitoral glands do not seem to have a role in production of this pheromone.