ANATOMICAL STUDIES OF THE HUMAN CLITORIS

Abstract

PURPOSE: Endogenous or exogenous testosterone exposure to the fetus during gestation may result in masculinization of the external genitalia. Surgical correction requires a clear understanding of normal female anatomy. We report observations from our anatomical dissections on which we base our approach to reduction clitoroplasty. MATERIALS AND METHODS: A total of 14 normal human fetal clitoral specimens at 8 to 24 weeks of gestation were serially sectioned after formalin fixation. Every tenth section was stained with Masson's trichrome, smooth muscle alpha-actin and the neuronal markers PGP 9.5 or S-100. Computer reconstruction using imaging software permitted 3-dimensional analysis of the nerves, corporeal bodies and glans clitoris. These specimens were compared with 2 obtained postnatally at feminizing genitoplasty. RESULTS: The normal fetal clitoris consists of 2 corporeal bodies with a midline septum. The ultrastructure of the female corporeal bodies is similar to that of the male counterpart. The glans clitoris forms a cap on top of the distal end of the narrowed corporeal bodies. There is a midline septum starting on the ventral aspect and extending approximately halfway into the glans. Large bundles of nerves course along the corporeal bodies with the highest density on the dorsal aspect or top. No nerves were noted at the 12 o'clock position, although nerves extend completely around the tunica in a fashion similar to that of the fetal penis. Glans innervation is provided by multiple perforating branches entering at the dorsal junction of the corporeal body and glans. The lowest density of nerves in the glans is on the ventral aspect in juxtaposition to the glans septum. In surgical specimens obtained from patients with congenital adrenal hyperplasia nerves were adjacent to the excised tunica of the corporeal bodies, especially on the lateral aspect. CONCLUSIONS: A clear understanding of the anatomy of the human clitoris is important for surgical reconstruction. As in the human penis, nerves in the clitoris form an extensive network around the tunica of the corporeal body with a nerve-free zone at the midline 12 o'clock position. Care should be taken to preserve all nerves. Reduction of the glans clitoris should not violate the extensive innervation that predominates on the dorsal aspect of the glans. The normal clitoris has corporeal bodies that are smaller but analogous to those of the penis. One may consider their function when extensive resection is considered.