In plain words
A tight junction is a seal between neighboring cells. In the breast, the cells that make milk are joined by these seals, which help keep milk inside the milk-making tubes. Around the time milk comes in, the seals close more firmly and limit milk slipping back into the blood. Later, during weaning, the seals loosen again, and the breast changes. Mothers may notice these changes as shifts in milk volume or in how the breast feels. Tight junctions are a physiology topic, not a sign of trouble. Much of what is known comes from laboratory and milk-measurement studies, and what it means for daily feeding is still being studied.
The deeper version
Tight junctions are multiprotein complexes, including claudins, occludin, and ZO-1, that seal the paracellular space between mammary epithelial cells. Closure at limits paracellular flux of sodium and plasma proteins into milk, and their opening during contributes to the change in milk composition. Milk sodium and the sodium-to-potassium ratio are used as markers of junction integrity (Neville and Morton, Journal of Nutrition, 2001). Opening of the junctions also occurs with and with long gaps between milk removals, which changes milk composition. Direct study in humans is limited, and much of the detail comes from animal and milk-composition studies.
Where it comes up
- How breastfeeding works: supply and demandFeeding Your Baby
- When your milk comes inFeeding Your Baby
- Weaning: gradual, abrupt, and baby-ledFeeding Your Baby
What mothers here say about tight junction
No one has posted under this term yet.
Sources
- Neville MC, Morton J — Physiology and endocrine changes underlying human lactogenesis II. Journal of Nutrition 2001