Light micrograph of a normal human epididymis, a tube connecting the testis to the vas deferens, in which sperm matures. The epididymis is a coiled duct about 7 metres long, seen here in various planes of section. The duct lumen (white spaces) contains closely packed spermatozoa (stained red). The epithelial lining of the duct wall projects stereocilia (blue lines) into the luminal space. The epithelium itself contains elongated columnar cells & rounded basal cells. The duct is surrounded by a layer of smooth muscle (dark blue). The cells beyond are connective tissue. Magnification: x50 at 35mm size.