EFFECT OF CASTRATION ON THE REPRODUCTIVE PHEROMONES OF MALE MICE

Abstract

It has been stated that the male mouse retains both the Whitten effect (control of the oestrous cycle) and the Bruce effect (control of implantation) to some extent after castration (Bruce, 1959, 1960; Parkes & Bruce, 1961). Subsequent observations failed to confirm either of these early claims. Further experiments on the relation between the gonads and pheromones have now been completed. The mice and the general procedure have been described elsewhere (Bruce, 1963). In the tests reported here the castrated males and the females belonged to the P strain, the stud males to the TO strain. Development of pheromone activity The capacity of the young male to inhibit implantation probably develops at about the same time as sexual maturity. Young males, aged between 3 and 4 weeks, failed to block pregnancy in females exposed to them alone (one