Light micrograph of a section through an epididymis, a tightly coiled tube that connects the testicles to the vas deferens. Sperm cells mature and are stored in the epididymis. Its highly coiled shape makes it appear as multiple circles when sectioned. The inside of the duct is lined with pseudostratified epithelium (light pink with purple nuclei). Within the lumen (white) of the duct are the sperm cells (purple). The duct is surrounded by a layer of smooth muscle (red). Magnification: x100 when printed at 15 centimetres wide.