Sebaceous gland. Light micrograph of a section through breast tissue showing a sebaceous gland. These glands produce an oily protective substance called sebum. At top is the duct (white, lined with purple-staining tissue) which connects to the surface of the skin. The glandular cells which produce the secretion are not clearly seen. Sebaceous glands are found at the base of hair follicles and on sensitive skin areas: in this case, the pigmented area around the nipple (the areola). Magnification unknown.