Mammary glands are special glands found in all mammals. In female mammals, the mammary glands produce milk. They are one of the major features that distinguish mammals from other kinds of animals (see Mammal ).
In males, the mammary glands remain undeveloped. In female human beings, they enlarge and develop at the beginning of adolescence. The gland itself consists of several lobes (compartments) surrounded by cells of fat. The amount of fat determines the size of the mammary glands. The lobes are made up of smaller lobules, also called acini, which are lined by cells that secrete milk. Many ducts (tubes) are connected to these lobules. The ducts combine and form several main ducts that empty milk from the mammary glands at the nipple. Mammary gland development and milk production are controlled by certain chemicals called hormones.
