deferens

The vas deferens, or ductus deferens, is a muscular duct of the male reproductive system that transports mature sperm from the epididymis to the ejaculatory ducts during ejaculation. It is a component of the spermatic cord and traverses the inguinal canal.

Anatomy: It measures about 40–45 cm in adults. The wall comprises an inner mucosa with pseudostratified columnar epithelium, a thick muscular coat with three layers (inner longitudinal, middle circular, outer longitudinal), and an external connective tissue adventitia. The lumen is narrow and often folded.

Course: The vas deferens originates at the tail of the epididymis in the scrotum. It ascends within the spermatic cord, enters the pelvic cavity via the inguinal canal, courses posterior to the bladder, and ends by uniting with the duct of the seminal vesicle to form the ejaculatory duct within the prostatic urethra.

Function and physiology: During ejaculation, sympathetic-driven peristaltic contractions of the smooth muscle propel sperm along the duct. The vas deferens stores sperm temporarily and provides a transit pathway; secretions contributing to semen primarily arise from the seminal vesicles and prostate.

Development and clinical relevance: The vas deferens develops from the Wolffian (mesonephric) duct. Clinically, interruption of its duct is achieved in a vasectomy for contraception. Congenital absence or obstruction can cause infertility; congenital bilateral absence of the vas deferens (CBAVD) is a known association with cystic fibrosis.