A convoluted duct extending from the ductuli efferentes draining the testicular lobules to the ductus deferens. The tightly coiled seminiferous tubules, about 17 feet in length, packed under the thick (~500 mm) tunica albuginea, store spermatozoa until they develop motility. Smooth muscle cells at the proximal end of the epididymis undergo slow, rhythmic contractions which gently convey spermatozoa toward the ductus deferens.