Epididymis

Function

The epididymis is a 6 m coiled duct compressed against the testis' posterior border — the place where immature sperm learn to swim and to fertilise. Over 12 days in its head, body and tail, sperm gain motility as their cytoplasmic droplet sheds and their membrane matures under androgen influence.

Its narrow lumen (a third of a millimetre) and single delicate duct make it vulnerable: epididymitis is the young man's commonest scrotal infection, and its tail continues seamlessly into the vas deferens.

Blood supply

Testicular artery's epididymal branches.

Nerve supply

Sympathetic T10–L1; ilioinguinal nerve to the overlying scrotum.

Clinical relevance

Epididymitis

Chlamydia or E. coli inflames the duct — subacute scrotal pain with a swollen, tender epididymis (unlike torsion's sudden strike).

Obstructive azoospermia

Congenital absence (CFTR mutations) or scarring blocks it — sperm retrieval and IVF overcome it.