epididymis

Embryologically, the epididymis develops from the mesonephric (Wolffian) duct, along with the vas deferens, seminal vesicles, and ejaculatory ducts. Sperm produced in the seminiferous tubules travel through the rete testis and efferent ductules into the epididymis, where they undergo functional maturation, gaining motility and fertilizing capacity, and are stored until ejaculation. The epididymal epithelium (pseudostratified columnar with stereocilia) absorbs fluid and secretes glycoproteins that aid sperm maturation.

Clinically, epididymitis presents with unilateral testicular pain, swelling, and tenderness, often with a positive Prehn sign (pain relief with testicular elevation), distinguishing it from testicular torsion (which has a negative Prehn sign and requires urgent surgical intervention). In sexually active men <35, common pathogens are Chlamydia trachomatis and Neisseria gonorrhoeae; in men >35 or those with recent urinary instrumentation, E. coli and other coliforms are more common. Epididymitis is treated with antibiotics targeting the likely pathogen (e.g., ceftriaxone plus doxycycline for STI-related cases). Epididymal cysts and spermatoceles are common benign findings, usually located in the head of the epididymis and often incidental. Congenital absence of the vas deferens (associated with cystic fibrosis) can also affect epididymal function and fertility. Ultrasound with Doppler flow is the key diagnostic tool to differentiate epididymitis from torsion.