Epididymis. Light micrograph (LM) of a section through an epididymis, the tube connecting the testis to the vas deferens, in which sperm matures. The epididymis consists of a coiled duct about seven metres long. Its highly coiled shape makes it appear as multiple circles when sliced transversely. The lumen of the duct (white) is lined with pseudostratified epithelium (pink), which is made up of columnar cells with elongated nuclei and rounded basal cells with circular nuclei. The fibres extending into the lumen are stereocilia. The duct is surrounded by a layer of smooth muscle (red). Magnification: x150 when printed 10cm wide.