1. Mammary glands or breasts are paired structure that have undeveloped duct system and adipose tissue.

2. When a woman gets pregnant, the secretion of oestrogen and progesterone increases. This develops a glandular system in the mammary glands which leads to the production of milk.

3. The glandular tissue of each breast, forms mammary lobes consisting of clusters of cells known as alveoli.

4. These alveoli cells start secreting milk that is stored within the cavities of the alveoli.

5. These cells further open into mammary tubules and join to form a mammary duct.

6. A number of mammary ducts join together in order to form a mammary ampulla from which the milk is sucked out.