How do muscle contractions move sperm through the ductus deferens?

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Front view anatomical diagrams of the male and female reproductive systems, with labeled organs including penis, testis, prostate gland, uterus, ovary, and vagina. — human reproductive system Organs and structures of the male and female reproductive systems.

The ductus deferens is a thick-walled tube that transports sperm from the epididymis toward the urethra during the emission phase of ejaculation.

Because sperm cells are not capable of self-movement while stored in the male reproductive system, they rely on muscular contractions for transport. The walls of the ductus deferens contain three layers of circular and longitudinal smooth muscle fibers. These fibers facilitate the movement of sperm through peristaltic contractions—rhythmic, wave-like contractions that push the sperm and accompanying fluids toward the ampulla and eventually into the prostate and urethra.123