SENSORY INNERVATION OF THE HUMAN PENIS

Z. Halata and A. Spaethe

Department of Functional Anatomy
University of Hamburg (UKE)
Martinstrasse 52, 20246 Hamburg
Germany

[CIRP Note: This article is mis-named. In reality, only the innervation of the glans penis is described. No mention is made of the important nerves in the foreskin. This file does not include two illustrations published with the original article.]

INTRODUCTION

Male reproductive behaviour has a complex neural organization. The penile erection and ejaculation require the integration and proper sequencing of somatic, sympathetic, and parasympathetic innervation (Johnson and Halata, 1991). In the present poster we try to answer two questions: 1. which type of sensory nerve endings occur and 2. how they are distributed. We have concentrated on the sensory nerves of the glans penis.

MATERIAL AND METHODS

In total 4 specimens of human penis were studied. One penis was fixed in 10% neutral-buffered formaldehyde, after embedding in paraffin, 8µm thick sections were obtained and stained with a silver impregnation technique (Spaethe, 1984). Small cubes (side length ca. 3 mm) from three cases of sex reversal between 22 and 28 years, were processed for electron microscopy.

RESULTS AND SUMMARY

The glans penis skin is covered by a thin keratinized stratified squamous epithelium (Fig. 1). The epithelium has rete ridges varying in height depending on the region of glans and the age. The epithelium over the ventral surface surrounding the frenulum is thinner than that of the dorsal aspect. The rete ridges are higher and narrower in younger than in older individuals.

The dermis underlying the epithelium consists of a dense connective tissue. The papillary layer forms the overlying rete ridges. The dense reticular layer of the dermis blends with the trabeculae separating the blood sinuses of the corpus spongiousum. Sensory nerve endings in the skin of glans penis are located in all tissue layers. In the epidermis and dermis free nerve endings are to be found (Fig. 1 asterisks); in the dermis genital end bulbs (Fig 1 arrows; Fig 2 asterisks), Pacinian corpuscles and rarely Ruffini corpuscles can be identified. Free nerve endings are located throughout the glans penis ad represent the most common type of sensory nerve endings. They are derived from thin myelinated axons (diameter 1-3 µm) or from unmyelinated C fibers. Two different types of genital end bulbs are to be recognized. Corpuscles tightly abutting the overlaying epithelium are small and lack a perineural capsule. Large genital end bulbs are situated deeper in the dermis and are completely surrounded by a multilayered perineural capsule (Fg. 2-2). Occasionally small and large Pacinian corpuscles are to be found deep in the dermis of the dorsal aspect and corona glandis region. Ruffini corpuscles are only occasionally to be observed in the dense connective tissue of the dermis by means of electron microscopy. The afferent myelinated axon has a diameter of 2-4 µm (Fig. 2-1). Most of the corpuscles have an incomplete perineural capsule.

In contrast to typical glabrous skin, the so-called mucocutaneous tissue of the glans penis contains a predominance of free nerve endings, numerous genital end bulbs and rarely Pacinian and Ruffinian corpuscles. Merkel nerve endings and Meissner corpuscles are not present.

REFERENCES