PHEROMONALLY ACCELERATED PUBERTY IS ENHANCED BY PREVIOUS EXPERIENCE OF THE SAME STIMULUS

The influence of rearing conditions on pheromone-induced puberty accel eration was tested on Swiss mice. Litters were reared in one of three conditions: with either both parents, or with two females, or finally with two females in the presence of urinary pheromonal cues from adult males, which are known to induce puberty acceleration. Nine days afte r weaning the females were exposed to either prepubertal or adult male urine. In the groups reared with either both parents or with two fema les and the pheromonal cues from stranger males, females treated with adult male urine presented heavier uteri and more cornified vaginal sm ears than females reared in the same conditions but subsequently treat ed with prepubertal males urine. In the group reared simply with two f emales, the differences in both uterus weight and vaginal smears did n ot reach statistical significance. The data support the notion that ea rly experience of pheromonal cues may influence the response to pherom ones in a later period, even if the preweaning exposure to males had n o direct influence on early signs of puberty onset.