Effects of dorsal penile nerve transection upon the sexual behaviour of the male marmoset (Callithrix jacchus).

The sexual behaviour of 7 adult male marmosets and their ovariectomized partners was observed during pair-tests before and after bilateral dorsal penile nerve transection (n = 4) or a sham operation (n = 3). After transection of the dorsal penile nerves, males mounted more frequently and the initial mount of each test was more prolonged. Males continued to orientate correctly during mounts and to make rapid pelvic thrusts, with the erect penis close to the vaginal orifice. However, the deep pelvic thrust required to attain intromission was abolished. Intromission was rarely observed postoperatively and ejaculation occurred only twice, in one male. These effects were not observed in sham-operated males. The results show that afferent impulses from the penis, travelling through the dorsal penile nerves, play a vital role in the coordination of intromission and ejaculation in this primate species.