What is a breast?

The female breast is a symbol of womanhood and femininity but, at the same time, it has an important function. It is an organ that, under appropriate stimulation, will produce milk.

  1. Chest wall
  2. Pectoralis muscles
  3. Lobules
  4. Nipple surface
  5. Areola
  6. Lactiferous duct
  7. Fatty tissue

Shape and Form

The shape and form of breasts is determined by your genes, and is thus inherited from your parents. Factors that determine the appearance of our breasts are:

The amount of fat in the breast. The amount of glandular tissue in both small and large breasts is about the same. It is mainly the fat that determines the size of breasts.

That is why, when we lose weight, the size of our breasts will often also decrease.

The shape of the breast is strongly influenced by a triangle of skin which extends down from the chin, fans out over the breasts and is supported by a fan-shaped muscle.

Breast firmness – not to be confused with breast density – is dictated by certain ligaments.

By using a good skin oil or cream we can look after the skin of our breasts. By doing the correct exercises, such as push-ups and swimming (excellent breast toners!) and by eating a healthy diet, the condition of the breasts can, to a certain extent, be maintained.


Breasts are directly linked to the body’s hormone producing endocrine system. Hormones are chemical messengers that circulate in the blood stream and act on organs.

At birth the breast is just a little nipple bud with essentially no function. At puberty, due to the hormones oestrogen and progesterone, the breasts begin to enlarge. The hormonal

ups-and-downs of the menstrual cycle are also due to oestrogen and progesterone levels. The breasts enlarge premenstrually and occasionally become painful. This pain disappears with the onset of menstruation, as the breasts contract.

During pregnancy, the pituitary gland creates the hormone prolactin which kick starts and stimulates milk production. Prolactin is stimulated by oestrogen and inhibited by progesterone. When a woman gives birth her progesterone levels drop, allowing oestrogen levels to rise thereby stimulating the production of prolactin that, in turn, stimulates the formation of milk.

Breast milk comes from tiny glands (lobules) within the breast. Each breast has about eighteen lobules of glandular tissue. Lobules resemble bunches of grapes with each grape being a milk secreting unit called alveolus (pleural: alveoli).

The feeding baby, by sucking on the nipple, expresses milk from the breast ducts, but it cannot get at the milk lying deep within the alveoli so another hormone, called oxytocin, comes into action. The sucking of the nipples sends messages to the hypothalamus part of the brain which tells the pituitary gland to produce oxytocin, and send it to the breast via the blood stream.

Breast Cancers

Almost all breast cancers arise in the alveoli. These cancers can be in situ (still within the lobules) or invasive. Invasive duct carcinomas occur in the lining of the ducts. Invasive (infiltrating) duct carcinomas are the most common type, accounting for over 90% of all breast cancers.

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