SEXUAL REFLEXES IN MALE-RATS - RESTORATION BY EJACULATION FOLLOWING SUPPRESSION BY PENILE SHEATH REMOVAL

Following removal of the penile sheath, adult male rats were able to copulate with receptive females. For the males that ejaculated, the number of mounts with and without intromission increased, but other pre-ejaculatory parameters of copulation were unchanged, suggesting that ejaculatory excitation is an additive function of penile contact with the vagina and with the penile sheath. Intact males held in the supine position with the penile sheath retracted displayed penile reflexes. Supine males lacking the penile sheath displayed no penile reflexes prior to copulation, but immediately after ejaculation there was a partial restoration of reflexes. Hence, the pressure of the penile sheath at the base of the penis is normally necessary for the evocation of reflexes in supine males. Following ejaculation, during a presumed condition of reduced supraspinal inhibition, the reflexes may be displayed without sheath stimulation. The penile sheath of the rat apparently contributes to copulatory behavior and to penile reflexes, but in rather different ways. © 1979.