Archive:Lactocyte: Difference between revisions

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Many of these processes are still under investigation. It is thought that nutrients are transported to alveoli by transport proteins on the membranes of mammary epithelial cells. Milk proteins are synthesized in the endoplasmic reticulum and packaged into secretory vesicles, alveolar cells add nutrients such as calcium, zinc, phosphate, lactose, and citrate, and the milk is transported from the lactocyte via exocytosis. Lipids are wrapped in a membrane and secreted as milk fat globules. Other transport proteins uptake nutrients from the blood and from interstitial fluid.<ref>{{Cite journal |last1=Montalbetti |first1=Nicolas |last2=Dalghi |first2=Marianela G. |last3=Albrecht |first3=Christiane |last4=Hediger |first4=Matthias A. |date=March 2014 |title=Nutrient Transport in the Mammary Gland: Calcium, Trace Minerals and Water Soluble Vitamins |url=http://link.springer.com/10.1007/s10911-014-9317-9 |journal=Journal of Mammary Gland Biology and Neoplasia |language=en |volume=19 |issue=1 |pages=73–90 |doi=10.1007/s10911-014-9317-9 |pmid=24567109 |issn=1083-3021}}</ref>

Mammary glands contain alveoli. Inside the alveoli of lactating females, a bulb-like lumen is lined by lactocyte cells, which secrete milk into the lumen, which is then squeezed out of the lobules, or groups of alveoli, into milk ducts as the infant suckling triggers muscle contractions.<ref>{{Cite web |title=NDC {{!}} Lactogenesis: secretory differentiation and activation of the human mammary gland |url=https://ndcinstitute.au/article/d9d9a92d-471b-4c1b-80de-bdc49cc3fc5f/lactogenesis-secretory-differentiation-and-activation-of-the-human-mammary-gland |access-date=2026-09-11 |website=ndcinstitute.au}}</ref> Nerve fibers near the areolar region respond to suckling and initiate a neuroendocrine reflex that initiates secretion of milk from lactocytes into the alveoli.<ref>{{Cite web |title=Lactation {{!}} Anatomy and Physiology II |url=https://courses.lumenlearning.com/suny-ap2/chapter/lactation/ |access-date=2026-09-11 |website=courses.lumenlearning.com}}</ref>

Mammary epithelial cells differentiate into lactocytes during the secretory differentiation stage of lactogenesis.<ref name=":1">{{Cite web |last=Physiology |first=Fetal and Neonatal |date=2024-03-22 |title=Drug Transfer During Breastfeeding |url=https://clinicalpub.com/drug-transfer-during-breastfeeding/ |access-date=2026-09-11 |website=Clinical Tree |language=en-US}}</ref><ref>{{Cite web |title=NDC {{!}} Lactogenesis: secretory differentiation and activation of the human mammary gland |url=https://ndcinstitute.au/article/d9d9a92d-471b-4c1b-80de-bdc49cc3fc5f/lactogenesis-secretory-differentiation-and-activation-of-the-human-mammary-gland |access-date=2026-09-11 |website=ndcinstitute.au}}</ref> Following differentiation, pregnancy hormones suppress the lactocytes, reducing their size and function. Upon delivery of the placenta, the resulting significant drop in progesterone allows prolactin to stimulate milk synthesis and secretion in the alveoli. Initially, there are large intercellular gaps between lactocytes, allowing high transfer of maternal plasma components to enter the milk, and colostrum - the initial, immature, and highly beneficial milk - is produced. As the intercellular gaps are bridged by an apical junctional complex and the number of lactocytes increase, they begin to produce “mature” breast milk.<ref name=":1" />

Lactocytes secrete milk continuously, but slowly.<ref name=":2" />As the lactocytes produce milk globules within the alveoli, intra-alveolar pressure stretches the lactocytes which prevents the cells from producing and “pinching off” fatty globule membranes, causing a reduced fat content. As the milk is removed, pressure reduces, and the fat content of the milk increases. <ref>{{Cite web |title=NDC {{!}} Limitations of the bioactive factors Feedback Inhibitor of Lactation model |url=https://ndcinstitute.au/article/781aa171-6c68-49b5-ab73-ae372fa0769b/limitations-of-the-bioactive-factors-feedback-inhibitor-of-lactation-model |access-date=2026-09-11 |website=ndcinstitute.au}}</ref>

The feedback inhibitor of lactation (FIL) protein acts by reversible blockade to limit secretion by lactocytes. The protein and its effect on lactocytes are part of the feedback process whereby breast milk supply adapts to changing demand by the breastfeeding infant.<ref>{{Cite journal |last1=Peaker |first1=M. |last2=Wilde |first2=C. J. |date=July 1996 |title=Feedback control of milk secretion from milk |journal=Journal of Mammary Gland Biology and Neoplasia |volume=1 |issue=3 |pages=307–315 |doi=10.1007/BF02018083 |issn=1083-3021 |pmid=10887504}}</ref>

== References ==

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