The ductuli efferentes from the testis perforate the tunica albuginea, and carry the seminal fluid from the testis to the epididymis. Their course is at first straight; they then become enlarged, and exceedingly convoluted, and form a series of conical masses, the conical lobules of epidiymis (coni vasculosi), which together constitute the head of the epididymis.
Each cone consists of a single convoluted duct, from 15 to 20 cm. in length, the diameter of which gradually decreases from the testis to the epididymis. Opposite the bases of the cones the efferent vessels open at narrow intervals into a single duct, which constitutes, by its complex convolutions, the body and tail of the epididymis. When the convolutions of this tube are unravelled, it measures upward of 6 meters in length; it increases in diameter and thickness as it approaches the ductus deferens. The convolutions are held together by fine areolar tissue, and by bands of fibrous tissue.