Anatomy of Breast

Writer : Hardeep Kaur
Edited by : Darchaini A/P Rajagopal
Checked by : Dr Hairin Anisa Bt Tajuddin

The breast is made up of a number of different structures that all have specific functions. The mammary glands are the most important and largest group of tissues in the breast, as they produce milk (mammogenesis). Mammogenesis is the process of developing and growing a mammary gland in preparation to produce milk, this is completed as the pregnancy enters its third trimester. A girl experiences a process in which their breast tissue goes from being relatively small to large and developed during puberty when mammary glands are exposed to estrogen.  

Mammary glands are responsible for producing and storing hormones like estrogen, progesterone, and prolactin. The breast also contains other important tissues that are responsible for a number of different processes including: lymphatic vessels (a type of tissue in charge of fighting infections), muscle fibers, fat cells, and blood vessels. All these components work together to make up the entire structure of the breast. Breast tissues in the breast are made up of mammary glands, connective tissue, glandular tissues such as lobules, alveoli or milk sinuses (ducts) and muscle. 

The breast starts as a bud of tissue that grows into either one or two grape-sized lumps called breast buds, which are in the upper parts of the chest near the armpits at about six months gestation. Mammary glands inside each breast then grow under hormonal stimulation from estrogen during puberty. Breast cells develop around mammary gland ducts with different functions including secreting milk when stimulated by oxytocin. 

The breast is primarily responsible for milk production, but it also provides some additional functions such as body temperature regulation for baby while breastfeeding, protection from injury and  support of other structures in the chest cavity (such as ribs).  

Lobules in in breast anatomy are the small, grape like structures where milk is produced and stored. Milk ducts in breasts are the tubes that breastmilk travels through. They carry milk from the lobules to the nipple. The function of areola at the breast is to protect and provide a cushion for the breast during breast feeding. Nipples are external structures that breastfeed babies use to suckle breast milk. They provide an exit for breastmilk and allow it to be expressed or leak out of your nipples. Montgomery’s tubercles are sebaceous glands that appear as small bumps around the dark area of the nipple. These glands create a protective oil to prevent germs from invading breast milk ducts and they keep skin moisturized. Studies found that between 30-50% of pregnant women notice Montgomery’s tubercles. 

Breastmilk is produced by breast tissue, which is made up of mammary glands. A normal female’s breasts contain 15 to 20 lobes per breast (30–50 total lobules) that are connected to the large ducts, these produce milk for feeding babies, about 12–15% will be involved in lactation at any given time while others rest. 

The milk comes from small sacs in the breasts called alveoli. The alveoli take your blood sugar, protein, and fat to convert them into breastmilk. This process is triggered by the hormone prolactin in response to its release from the pituitary gland. Oxytocin stimulates the myoepithelial tissues around the alveoli to contract and push the milk to the ducts. This passing of the milk down the ducts is called the “let-down” (milk ejection) reflex. Oxytocin is the hormone which seizes breast cells and causes breast milk ejection, it also encourages labor to progress, stimulate lactation and improving bonding between a mother and child. 

Prolactin is the hormone which signals breast cells to produce breast milk after childbirth, also hormones that control the ovaries, and which can affect menstrual periods, sexual functions and fertility. 

A pregnant mother will make plenty of prolactin but less oxytocin so her breasts start producing colostrum before birth and it has more protein than any other type of maternal breastmilk, this provides extra energy for the developing fetus and helps pass on antibodies from mom to baby. Breastmilk starts to be made in the duct system after 16 weeks of gestation, so even if your baby arrives prematurely you can still provide for them and breastfeed. 

A postpartum mom will also need to breastfeed often in order to supply maximum colostrum to new-born baby & continue stimulate milk production.  

Breastmilk has 98% water with complete macronutrients (lactose, protein & fat) that provide calories & complete micronutrients for your baby’s growth & development. It also contains immune factors which protect against infections in breastfed infants.  

Human breastmilk is the natural first food for all infants, providing nutrition and immune protection. The taste, nutrients & amount of breastmilk change throughout a feeding depending on what your baby needs at that moment. Breastmilk also provides hormones, enzymes, antibodies, vitamins and minerals not found in infant formula or cow’s milk-based drinks, these substances help protect an infant from illness during their vulnerable early years of life.