Library · Physiology
Function of the breast
Make it clearer
The main job of the breast is to produce milk, and two hormones split that work into separate assignments.
The milk itself is made in the terminal ductal lobular units, the clusters of glands where each duct ends. What puts them to work is prolactin: it makes the mammary ducts grow, it multiplies the epithelial cells, the ones that line those ducts on the inside, and it triggers the building of the milk proteins. Prolactin is the hormone of production.
The other one is oxytocin, and its task is not to make milk but to move it out. When a baby suckles, the touch on the nipple sends a signal to the hypothalamus, an area of the brain, and that signal releases oxytocin, which brings on the ejection of the milk. That is why mothers notice the milk letting down shortly after the baby latches on: one hormone had it ready and the other opened the way.
In brief
Milk is produced in the terminal ductal lobular units, the glandular clusters where each breast duct ends, and it is made in response to prolactin.
Prolactin stimulates the growth of the mammary ducts, drives the proliferation of epithelial cells, and induces the synthesis of milk proteins.
Oxytocin handles a different task, ejection: tactile stimulation of the nipple during suckling sends signals to the hypothalamus and triggers oxytocin release.
Sources (2)
- National Center for Biotechnology InformationHistology, Mammary Glands. StatPearls
- National Center for Biotechnology InformationPhysiology, Lactation. StatPearls
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