Final answer:
The mammary glands are complex structures with 15 to 25 lobes that produce milk, containing ducts that lead to the nipple. They are modified sweat glands, with milk production being regulated by hormones including prolactin.
Step-by-step explanation:
The human mammary glands are essential parts of the female reproductive system that produce milk to nourish a newborn. These glands are structurally complex, consisting of 15 to 25 lobes per gland. These lobes contain ducts that connect to the nipple, through which milk is supplied to the nursing child; this milk is both nutrient- and antibody-rich, crucial for the child's development and protection against disease. The size of the breasts mainly depends on the volume of fat present, but the actual production of milk happens in the glandular tissue.
Mammary glands are considered modified sweat glands comprising a system of lactiferous ducts and lobules, which are radially organized around the nipple. Each lobule houses alveoli, which are balloon-like structures lined with milk-secreting cells (lactocytes). Myoepithelial cells surround the alveoli and help expel the milk into the ducts and eventually into the lactiferous sinuses, which open at the nipple.
The production of breast milk is a hormonally regulated process, primarily under the control of prolactin from the pituitary gland. This hormone not only triggers milk production but is also important in drawing nutrients required for milk synthesis. The structure and function of the mammary glands undergo significant changes during pregnancy and lactation, reflecting the body's preparation for feeding the infant.