any of the compound accessory reproductive organs of female mammals that occur in pairs on the chest or ventral surface and contain milk-producing lobes with ducts that empty into an external nipple, becoming functional when young are born and secreting milk for the duration of suckling.
mammary glandn. Any of the milk-producing apocrine glands typically occurring in pairs in female mammals and consisting of lobes containing clusters of alveoli with a system of ducts to convey the milk to an external nipple or teat.
(mām'ə-rē) One of the glands in female mammals that produces milk. It is present but undeveloped in the male. In most animals, the gland opens onto the surface by means of a nipple or teat. Mammary glands number from 2 to 20, depending on the species.