Tunica vaginalis

It is the remnant of a pouch of peritoneum which is pulled into the scrotum by the testis as it descends out of the abdominal cavity during foetal development.

Anatomy

Visceral layer

The visceral layer of tunica vaginalis of testis (lamina visceralis tunicae vaginalis testis) is the portion of the tunica vaginalis that covers the testis and epididymis. It is the superficial-most of the three layers that constitute the capsule of the testis, with the tunica albuginea of testis situated deep to it. Posteriorly, the visceral layer does not line the surface of the testis - instead, it passes onto the epididymis where the latter attaches to the testis before continuing onto the inner surface of the scrotum as the parietal layer.

Parietal layer

The parietal layer of tunica vaginalis of testis (lamina parietalis tunicae vaginalis testis) is the portion of the tunica vaginalis that lines the inner surface of the scrotum. It is supported by the internal spermatic fascia.

Cavity of the tunica vaginalis

The cavity of the tunica vaginalis (also: cavum of the tunica vaginalis, or cavum vaginale) is the cavity between the visceral layer and the parietal layer of tunica vaginalis. It is normally occupied by a small amount of clear, lightly coloured fluid.

The volume of the fluid in the cavity may increase abnormally when lymphatic drainage is impeded (due to inflammation, neoplasm, or trauma).