Breast: how it is made and how it produces milk

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How does the breast produce milk

The breast is a set of various tissues and each one has its own specific function:

  • Glandular tissue which produces milk
  • Adipose tissue, which is normally the one responsible for the size of the breast and which then "transforms" into milk. They saw that in many breasts the fat almost disappears to make room for the alveoli that change due to galactopoiesis.
  • Connective tissue which crosses the various ligaments supports the breast and anchors it to the chest
  • Blood vessels and lymphatic system, the cells of the alveoli are completely enveloped by capillaries

The cells that produce milk form the alveoli, these resemble a small bag that serves to contain the milk produced, in turn the alveoli pour the milk into the milk ducts or galactophores. The more alveoli form a lobule, the more lobules the lobes form.
In a normal breast there are about 15-20 lobes with as many milk ducts that gradually merge to become about ten as they reach the nipple. Before emerging into the milk pores (the pores are the holes from which the milk comes out) the milk ducts form the milk sinuses that appear
like cisterns where a little milk accumulates, and it is the area that is "squeezed" from the baby's mouth while breastfeeding. However, recent studies question this anatomical aspect.

The structure is like that of a tree, starting from the nipple and going towards the periphery, the whole branches and gradually increase the milk ducts:

  • 10 pores in the nipple → 15-20 milk ducts → 15-20 lobes → more than 20 lobules per lobe →

This structure is generally common to all women. 
The variety of breast size among women is mainly due to the amount of accumulated fat.

When breast milk is formed

With pregnancy, the breast completes its development; breast size increases, skin becomes thinner and veins are seen more. The areola becomes darker and the nipple becomes mobilized and more prominent; the Montgomery glands (those pyrulins that feel in the nipple as if they were pimples) which begin to produce a substance that will have the task of lubricating the nipple during sucking.

Furthermore in the second half of pregnancy often women start producing the colostrum, a kind of yellowish milk that precedes the 'classic' milk.

When milk starts coming out of the breast

The breasts primarily respond to two hormones: prolactin and oxytocin.

Prolactin is secreted by the pituitary when the nipple is stimulated, but it is also produced during pregnancy but has no effect because it is "silenced" by the high amount of estrogen and progesterone produced by the placenta. Prolactin is then produced every time the breast is stimulated (sucking or squeezing) and then frequent feedings stimulate milk production. Furthermore, the prolactin levels are much higher during the night due to the absence of light (it's one of those hormones that work well in the dark) and consequently milk production is also greater, to further stimulate theWhen producing milk, the breast can be stimulated at night as well as during the day - often attacking the baby.

Reduction of milk production, causes

  • Excessive nicotine consumption (too many cigarettes) can affect prolactin levels by lowering them and therefore reducing milk production.
  • If the breast is not emptied when full, a factor is released that inhibits prolactin avoiding overfilling, the prolactin inhibiting factor is called PIF.
  • Some moms often complain of a decrease in milk production after having a strong one breast engorgement which causes a reduction in prolactin production.

Oxytocin is also stimulated by nipple sucking, but also by an orgasm or a positive thought. Its synthesis is inhibited, for example by stress or something that worries us.

When a woman is breastfeeding, the oxytocin produced causes the milk to be ejected into the ducts and the baby does not have much difficulty breastfeeding, however this mechanism also occurs in the other breast and it often happens that milk comes out during the breastfeeding.
The same thing happens after an orgasm or the thought that the baby may be hungry, for example when the woman is out and feeding time is approaching, but it is not something that happens for all women and on all occasions.

It is a very shy hormone and this explains how difficult it can be for a mother to start a good breastfeeding in a context where she feels mistrust, fear, and simply not being able. Contact with the baby can help the production of oxytocin, see it also in photos, for example, some mothers who pump milk for a neonatal baby are advised to pump milk while looking at a picture of the baby.
Oxytocin also acts on the uterus by causing it to contract. These contractions are felt especially during the first week after childbirth or as long as the uterus is still large compared to normal. In women who have already had at least one birth, these contractions can also be painful and are called "uterine bites". It is also for this reason, the contraction of the uterus as a secondary effect, that the woman is advised to attach the baby to the breast immediately after delivery to prevent postpartum bleeding.


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