a. Description/Information. The mammary glands (breasts) are modified sweat glands which are located over the pectoralis major muscle between the second and the sixth ribs.

The interior of each mammary gland contains 15 to 20 compartments called lobes. These lobes are connected by fatty tissue called adipose tissue. The size of a female’s breasts is determined by the amount of adipose tissue in the breasts. The amount of milk a female produces after childbirth has nothing to do with the size of her breasts. Each lobe contains several smaller compartments called lobules. Lobules are made up of connective tissue containing milk-secreting cells named alveoli.

b. Functions in Pregnancy. A female’s breasts enlarge after the second months of pregnancy.

At the same time, the nipples become darker due to an increase in pigmentation. For the first three days after the infant’s birth, the breasts produce a thin, yellowish fluid called colostrum. This fluid is not as nutritious as breast milk but it serves to nourish the infant until the mother’s breast milk comes in on the third or fourth day.