Ligamentous structures in human glans penis

Abstract

The corpus spongiosum reportedly occupies a larger proportion of the human glans penis than does the penile body, embedding the end of the corpus cavernosus (CC). However, anatomic descriptions about the fibrous structures of glans penis in the literature cause confusion during dissection and reconstructive surgery. Forty-five penises of formalin-embalmed cadavers were dissected sagittally along the course of the distal urethra and observed macroscopically. Dense connective tissues adjacent to the fossa navicularis and spongiosum parts of the glans were cropped, and underwent Masson's trichrome and Verhoeff-Van-Gieson staining. Most (55.5%) of the specimens had distinct fibrous bands toward the distal tips of the glans penis, which elongated from the tunica albuginea of the CC. They comprised longitudinal collagen bundles continuous to the outer longitudinal layer of the tunica albuginea covering the CC and were intermingled with sparse elastic fibres. This architecture either did not reach the distal end of the glans penis (35.5% of cases), or was obscure or dispersed in all directions (9.0% of cases). The structural dimorphism and the variations in the ratio of dense connective tissue components of the fibrous skeleton are considered to contribute to the varying degrees of flexibility, distensibility and rigidity of the human glans penis.

Keywords: corpus cavernosus; corpus spongiosum; distal urethra; fibroskeleton; glans penis; tunica albuginea.

Figure 1

Gross observations of the glans penis dissected mid‐sagittally. (A) In half of the samples (N = 25), the ligamentous tissues (arrowheads) were laid on the urethra throughout the glans penis. The fibrous bands were discontinuous by the vessels (red arrows) or spongiosum tissues (asterisk). CC, corpus cavernosus; CS, corpus spongiosum; E, external urethral orifice; F, fossa navicularis; yellow arrow, distal urethra. (B) Ligamentous tissues (arrowheads) on the upper wall of the distal urethra not reaching the distal tip of the glans (N = 16). The tunica albuginea and ligamentous tissues in the glans penis appeared darkly pigmented in some specimens (right). (C) Dense connective tissues with undulated or radiating features appeared in the spongiosum parts of the glans penis (N = 4).

Figure 2

Histology of the ligamentous tissues throughout the glandular urethra. The lower image is a magnified view of the boxed area. Distinct fibrous bundles (black arrows) are elongated longitudinally from the outer layers of the tunica albuginea (red arrow) encompassing the apex of the corpus cavernosus (CC).

Figure 3

Regional distribution of the elastic fibres in the ligamentous tissues of the glans penis. (A) The lower image is a magnified view of the boxed area stained by Verhoeff‐Van‐Gieson. (B) Magnification of a box (B) in (A). A central region of the fibrous band consists of buckling collagen bundles impregnated with a few elastic fibres (arrows). (C) An abundance of elastic fibres with large diameters in the peripheral region of the fibrous band. (D) A high proportion of fine elastic fibres compared with (B) in the distal region of the fibrous bands.

Figure 4

Connective tissues of the glans penis without ordered fibrous bands macroscopically. (A) Malformation of the tunica albuginea covering the distal tip of the corpus cavernosus (CC) (red arrow). (B) Distributions of buckling small‐diameter collagen bundles despite the absence of distinct ligamentous bands on the distal urethra by gross observation. (C) Dispersed collagen bundles in all directions with space in the distal region of the spongiosum parts of the glans.

Figure 5

Schematics of ligamentous tissues of the human glans penis. (A) A firm trunk with buckling collagen bundles (red striped areas) supports the maintenance of shape and force during coitus. Flexibility during thrusting due to peripheral arrangement of elastic fibres (purple) could provide the required flexural stiffness. (B) Dense connective tissues consisting of concentrated collagen bundles formed compact trunks in the central glans (91% of cases) or were dispersed as sparse bundles penetrating the sinusoidal space (9% of cases). Red networks in the glans and the penile shafts indicate the fibrous frame consisting of collagen bundles. F, fossa navicularis.