Women’s breast consists of 15-20 sectors (share), around the nipple area like spokes in a wheel. Inside of the shares are areas of the smaller sizes, called slices. At the end of each segments are tiny “bubbles” in which milk is produced. These elements are connected by miniature “tubes”, called ducts, where the milk comes to the nipple.

Teat is at the center of pigmented area called areola. In the areola are tiny glands called Montgomery glands that provide lubrication of the nipple during breastfeeding. Intervals between the slices and ducts filled with fatty tissue. Inside the breast are no muscles, but under each of the gland are pectoral muscles covering the rib.

In each of the mammary glands are the blood vessels, as well as vessels in which the liquid flows, known as lymphomas. Lymph circulating in the body by a network of vessels, or lymphatic system, carrying cells that help the body to fight infections. Lymph vessels  “flows” to the lymph nodes.

Group of lymph nodes is located in the armpits, above the clavicle and the chest cavity. If breast cancer had time to spread to these nodes (see breast cancer staging), it means that cancer cells can be separated into other organs and tissues, migrating to lymphatic vessels system. Lymph nodes are present in many other parts of the body.

The development of the mammary gland and the performance of its functions are regulated by hormones estrogen and progesterone, produced in the ovaries. Estrogen contributes to lengthening of ducts and their branching, and progesterone - increasing number and size of slices, prepearing gland for feeding the child.

After ovulation, under the action of progesterone duct is sizing, blood vessels inside are growing and filling with blood. At this point, mammary glands are filled with fluid and become painful.