Clitoral sexual arousal: an immunocytochemical and innervation study of the clitoris.

OBJECTIVE: To further define neural pathways and mechanisms responsible for the arousing properties of the epithelium of the clitoris as well as related neural pathways associated with sexual arousal in a murine model.
MATERIALS AND METHODS: Adult female C57B1/6 mice were used for gross dissection, facilitated by resin injection of the vascular system, and silver staining, and immunostaining for S-100 and neuronal nitric oxide synthase (nNOS). We also comprehensively reviewed relevant published clinical and histological material from both human and non-human vertebrate studies.
RESULTS: The distal innervation consists of three nerve bundles: one related to the perineal region, one through the corpus cavernosum, and the third between the dorsal part of the clitoris and the urethra. Communicating nerve fibres were identified between the perineal, the corpus cavernous nerve (CN) and the dorsal nerve of the clitoris. Immunostaining for nNOS showed that the CN sends nNOS-positive fibres to join the dorsal nerve of the clitoris. In the same distal area of the clitoris, the connecting branches between the perineal nerve and the dorsal nerve of the clitoris are also nNOS positive.
CONCLUSIONS: A rich network of nerve bundles and terminal branches were identified and associated with nNOS immunostaining in the cavernosal tissue of the body of clitoris. NO control of vasodilatation and neuronal signalling between the CN and the dorsal nerve of the clitoris could contribute to the engorgement and subsidence of clitoral tissue. This supports the initiation of sexual arousal by tactile stimuli. The distribution pattern of the general and peptidergic innervation in the murine clitoris is similar to that of the penis.