Everyone has two mammary glands, but its tissue and ducts only develop in females. The sole function of these glands, commonly known as female breasts, is the production of milk. In males, these exocrine glands reside under their nipples in an undeveloped and nonfunctional state for a lifetime.
In women, each mammary gland develops into a mass of glandular, adipose and fibrous tissue. Regulated by the endocrine system, initial growth of this gland’s tissue and ducts is stimulated by a rise in estrogen and progesterone levels during puberty. And most women’s mammary glands will swell in size during pregnancy because of the increased circulation of these same hormones.
After puberty, milk is not usually produced by a mammary gland without hormonal changes associated with childbirth. The hormones that signal your body to make milk is pituitary gland secretion of prolactin and hormones originating from the placenta.
The process of milk production is called lactation. And nipple area suckling (breast feeding) leads to milk ejection by stimulating the release of oxytocin. Oxytocin has a contraction effect on mammary gland ducts. Milk continues to be produced during the course of breastfeeding because prolactin is secreted in response to its discharge. Stop feeding and within a couple of weeks lactation ends because the lack of prolactin no longer stimulates milk production.
The milk produced by your mammary glands not only provides nourishment, but infection protection to your baby as well. Infants are born with an immature immune system. Mammary gland milk supplies antibodies that are typical of natural immunity. This support helps protect against infecting pathogens that could otherwise cause some problems early on. In addition, breast milk is easily digested without the potential trouble formulas can cause.
During pregnancy and lactation you can expect your mammary glands to be swollen. However, they may naturally swell when female hormones fluctuate up during other circumstances, for instance before menstruation or after female hormone replacement therapy. Swelling within your breast may occur for abnormal reasons too, such as:
- cancer
- mastitis
- endocrine disorder
- Klinefelter’s syndrome
- benign tumor ~ fibroadenoma, intraductal papilloma
Galactorrhea can cause your breasts to enlarge unexpectedly. This health condition is marked by milk production during times when you are not breastfeeding. In fact men can experience it too, but rarely.