Final answer:
The breast, made up of glandular and adipose tissue, enlarges during puberty in females. It consists of mammary glands and fat, and facilitates lactation for feeding a nursing child. Hormones significant to pregnancy and breastfeeding lead to the development and milk production in the mammary glands.
Step-by-step explanation:
The mound of glandular and adipose tissue overlying the pectoralis major that enlarges at puberty within a female is the breast. The size of the breast is determined by the amount of fat deposited behind the gland. The mammary gland in the breast consists of 15 to 25 lobes, each of which contains ducts that terminate at the nipple. Those ducts transport nutrient- and antibody-rich milk, which aids in the development and protection of a nursing child.
Structurally, the breasts are comprised of adipose and collagenous tissue, with the mammary glands making up only a minor portion of the breast volume. However, during pregnancy, the mammary glands undergo extensive development in response to hormones like estrogen, growth hormone, cortisol, and prolactin. Clusters of alveoli form the lobules of the gland, and milk is secreted from lactocytes within the alveoli. It is then pushed into the ducts by contracting myoepithelial cells.
The lactation process is supported by the hormone prolactin, which is essential for establishing a breast milk supply, and allows the mother to provide crucial nutrition to the breastfeeding baby.