Innervation pattern and fiber counts of the human dorsal nerve of clitoris

Abstract

Even tough clitoris plays a critical role in female sexuality, we lack a precise understanding of qualitative and quantitative aspects of the innervation of the human clitoris. To address this issue, we dissected human clitorides from body donors and imaged them after staining with iodine with microCT for a macroscopic analysis. To resolve innervation patterns at the microscopic level we prepared thin sections of clitorides and stained them with trichrome azan to reveal the tissue structure combined with immunocytochemistry against Neurofilament H antibodies to reveal all axons and luxol blue labeling to reveal myelinated axons. We find the clitoral branch of pudendal nerve that innervates the clitoris not as single nerve, but as number of loose bundles. In the crus of the clitoris, about 12 such bundles can be recognized while about 32 bundles are present in the clitoral hemi-body. We counted on avarage 2917 axons in the crus of the clitoris (76% of which are myelinated) and 3137 axons in the hemibody of the clitoris (71% of which are myelinated). While the human clitoris receives only one third of the number of axons that innervate the human penis, an estimate of innervation density (per surface area) revealed that clitoris has approximately 6 times denser innervation compared to the penis. Thus, our study combines histology with microCT analysis provides detailed information on the number, myelination and innervation density of dorsal nerve of clitoris.