The muscle tissue of the nipple can be erect or relaxed. Most of the time nipples are partially erect, or flat, or inverted. How they have always been is the norm. Have a doctor check your breasts if the appearence of your nipples changed . Lymph channels collect the lymph fluid from breast tissues and drain into groups of lymph nodes in the armpit or axilla .
Blood veins go from the armpit to the heart and lungs.
Beneath the breasts the pectoralis muscle covers the chestwall. Stages in breast development Before puberty breast problems are virtually nonexistent. The glands and ducts of the breast develop and grow during puberty. Estrogen and progesterone , the two female hormones stimulate and regulate this growth. Estrogen and progesterone production in the body greatly increases during pregnancy .