→ A functional mammary gland is a characteristic of all female mammals.
→ The mammary glands are paired structures (breasts) that contain glandular tissue and variable amount of fat.

→ The glandular tissue of each breast is divided into 15-20 mammary lobes containing clusters of cells called alveoli.
→ The cells of alveoli secrete milk, which is stored in the cavities (lumens) of alveoli.
→ The alveoli open into mammary tubules.
→ The tubules of each lobe join to form a mammary duct.
→ Several mammary ducts join to form a wider mammary ampulla which is connected to lactiferous duct through which milk is sucked out.