Female Breast Anatomy

The Lactating Breasts

This page focuses on the anatomy of the breast, if you want more detail on the lactation process and how it works, you can read our page on breast milk production and/or stages of lactation. Hormonal processes of lactation discussed here

Cross Section of a Lactating Breast

Breast milk travels from the cluster of alveoli (the alveolus), also called "milk-producing cells," "glandular tissue," "mammary glands" or "milk glands," then into the milk ducts and then out of the nipple openings.

The breast has typically about 15 to 20 of these structures. There is fat also that surrounds these.

Oxytocin is the hormone released, that is responsible for the ejection of milk. Prolactin is the hormone responsible for milk production. The breast milk is continuously made.

Female Breast Anatomy
Latching on

The baby needs to take in the entire nipple and a large part of the areola for a good latch and good milk transfer. The nipple should touch the soft palate in a baby’s mouth.

With a good latch like this one, a mother is less likely to have sore or broken nipples; the nipple is protected by the soft palate.

This latch will also ensure that a baby is stimulating the areola (dark part around the nipple), which triggers the Oxytocin hormone, therefore, promoting increased milk flow.

A mother's nipple will elongate to about twice its regular length when drawn into a baby’s mouth.

Female Breast Anatomy
The Alveoli

The alveoli (milk-producing cells)

These are made up of milk gland cells around the end of a milk duct. The gland cells produce milk, and with the help of myoepithelial cells, the milk is ejected into the milk duct, which then travels down to the front of the breast.

Milk is produced during and between feedings. The first amount of milk that comes out is called foremilk, the milk further back in the alveoli and milk ducts is called hindmilk, which is more abundant in fat content as most of the fat globules have collected there as the milk passed through. This is why it is so important that a mother allows her baby to breastfeed on one breast, until it seems "empty," so that her baby can receive the substantial hindmilk too.

Learn more about hindmilk foremilk imbalance.

Female Breast Anatomy

nipples, types of nipples, inverted nipples, flat nipples, concave nipples

All women have different nipple sizes, but some women find it more difficult to breastfeed if they have flat or inverted nipples.

How to know if your nipples are flat or inverted

Other nipple variations

Nipples have several openings, through which the milk will flow.

Female Breast Anatomy
Lactogenesis and Mammogenesis

Breast growth during pregnancy

A mother that might have struggled with low milk supply, with her first baby, will usually have an increased milk supply with her second child. This is due to breast tissue increasing and maturing via a process called lactogenesis ( enabling milk secretion ) and mammogenesis (maturation of glands and ducts). This is especially true if the mother breastfed for at least two months the first time around.

Remember that the size of your breasts has absolutely nothing to do with the amount of breast milk produced. 

Changes include:

  • With every pregnancy, your breasts will increase in size, due to the increase in alveoli, which is needed for breast milk production. This is a result of the hormones released during pregnancy and afterward.
  • Blood supply to the breast during pregnancy will increase.
  • Veins may become darker and more visible through the skin on the breasts.
  • The Montgomery glands (small nodule like structures on the areola),  will start to produce an oily like substance that will lubricate the skin and also keep your breasts and nipples bacteria free.
  • The areolas may become darker and larger.
  • Nipples might become larger.

Learn more about dealing with blocked milk ducts.

Learn more about dealing with a nipple blister “bleb."

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