mammary gland

mammary gland One of the two halfmoon–shaped glands on either side of the adult female chest, which with fatty tissue and the nipple make up the breast. Within each mammary gland is a network of sacs that produce milk during lactation and send the milk to the nipple via a system of ducts. Undeveloped mammary glands are present in female children and in males. See also breast; lactation.