Library · Physiology
Breast involution
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Breast involution is the milk-producing tissue going into reverse.
At the ends of the breast ducts sit the secretory alveoli, clusters of tiny glands. Late in pregnancy those alveoli fill with milk, and what drives them to do it is prolactin, a hormone. When breastfeeding ends, the alveoli shrink, grow fewer, and finally disappear: a cluster of sacs that stops filling, shrinks, and finally falls apart.
Later there is a second regression. After menopause the breast shrinks again, and this time the reason is that the estrogen circulating in the blood drops. Even so, the gland never goes back to what it was before puberty.
In brief
When breastfeeding ends, the breast's secretory alveoli shrink, decrease in number, and disappear.
A cluster of sacs that stops filling, shrinks, and finally falls apart.
These alveoli had formed at the ends of the ducts and filled with milk under the influence of prolactin.
After menopause the breast shrinks again, this time because circulating estrogen falls.
Even so, the mammary gland never returns to its prepubertal form.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Thorax: Mammary Gland, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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