Enkephalin-immunoreactive nerve fibers in the feline genito-urinary tract.

Besides the classical neurotransmitters acetylcholine and norepinephrine the genito-urinary tract contains also neuropeptides. The distribution of substance P- and VIP-containing nerve fibers have earlier been described. Also enkephalin-immunoreactive nerve fibers occur in the male and female genito-urinary organs of the cat. The nerves are more numerous in male than in female genital tract. The prostatic gland and vas deferens receive the largest supply. In the female genital tract the enkephalin-immunoreactive nerve fibers are regularly seen in the smooth muscle layer of the cervix. Of special interest is the rich occurrence of the enkephalin nerve fibers among th nerve cell bodies in the para-urethral and cervical ganglia supporting the view that enkephalin may play a neuromodulating role.