(b) Explain the structure and function of mammary glands.

Explanation

Mammary glands are modified sweat glands present in both sexes. It is functional in females and rudimentary in males. In human, a pair of mammary glands is placed in the thoracic region. The glandular tissues and variable quantities of fat are present in mammary glands along with a median nipple. The nipple is surrounded by a pigmented area called areola. The areolar glands, modified sebaceous glands are present on the surface. They help in reducing the cracking of the skin of the nipple.
Each mammary gland consists of 2 - 25 lobes. They are separated by fat and connective tissues. Each lobe contains many lobules, which contain acini or alveoli lined by epithelial cells. Milk is secreted by the cells of alveoli, which opens into mammary tubules. Mammary duct is formed by joining the tubules of each lobe. Mammary ampulla is formed by joining several mammary ducts. The mammary duct is connected to lactiferous duct in the nipple. The lactiferous sinus is the expansion of lactiferous duct under the nipple and serves as a reservoir of milk. On the surface of the nipple, each lactiferous duct opens by a minute pore.