Archive:Lactocyte: Difference between revisions

'''Lactocytes''', also known as mammary epithelial secretory cells, are cells that synthesize and secrete milk within the mammary glands of lactating mammals.<ref>{{Cite web |title=Endosymbiont |url=https://www.endosymbiont.com/celltypes/lactocytes |access-date=2026-09-11 |website=www.endosymbiont.com}}</ref><ref name=":2">{{Cite journal |last1=Pang |first1=Wei Wei |last2=Hartmann |first2=Peter E. |date=2007-12-01 |title=Initiation of Human Lactation: Secretory Differentiation and Secretory Activation |url=https://doi.org/10.1007/s10911-007-9054-4 |journal=Journal of Mammary Gland Biology and Neoplasia |volume=12 |issue=4 |pages=211–221 |doi=10.1007/s10911-007-9054-4 |pmid=18027076 |issn=1573-7039}}</ref>

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 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" />