Archive:Lactocyte: Difference between revisions
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Revision as of 00:15, 13 October 2026
Template:Short description Template:Infobox cell
Lactocytes are cells that synthesize and secrete milk within the mammary glands of lactating mammals.[1][2] In preparation of lactation, lactocytes differentiate from luminal adaptive secretory precursor (LASP) cells found in the resting mammary gland.[3]
Milk synthesis
Many of these processes are still under investigation. It is thought that nutrients are transported to mammary 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.[4]
Structure
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.[5] Nerve fibers near the areolar region respond to suckling and initiate a neuroendocrine reflex that initiates secretion of milk from lactocytes into the alveoli.[6]
Origin and stages
Mammary epithelial cells differentiate into lactocytes during the secretory differentiation stage of lactogenesis.[7][8] 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.[7]
Milk secretion and regulation
Lactocytes secrete milk continuously, but slowly.[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.[9]
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.[10]
References
- ↑ "Endosymbiont". https://www.endosymbiont.com/celltypes/lactocytes.
- ↑ 2.0 2.1 Pang, Wei Wei; Hartmann, Peter E. (2007-12-01). "Initiation of Human Lactation: Secretory Differentiation and Secretory Activation". Journal of Mammary Gland Biology and Neoplasia 12 (4): 211–221. doi:. ISSN 1573-7039. PMID 18027076. https://doi.org/10.1007/s10911-007-9054-4.
- ↑ "Defining breast epithelial cell types in the single-cell era". Developmental cell 60 (17): 2218-36. 2025-09-08. doi:.
- ↑ Montalbetti, Nicolas; Dalghi, Marianela G.; Albrecht, Christiane; Hediger, Matthias A. (March 2014). "Nutrient Transport in the Mammary Gland: Calcium, Trace Minerals and Water Soluble Vitamins" (in en). Journal of Mammary Gland Biology and Neoplasia 19 (1): 73–90. doi:. ISSN 1083-3021. PMID 24567109. http://link.springer.com/10.1007/s10911-014-9317-9.
- ↑ "NDC | Lactogenesis: secretory differentiation and activation of the human mammary gland". https://ndcinstitute.au/article/d9d9a92d-471b-4c1b-80de-bdc49cc3fc5f/lactogenesis-secretory-differentiation-and-activation-of-the-human-mammary-gland.
- ↑ "Lactation | Anatomy and Physiology II". https://courses.lumenlearning.com/suny-ap2/chapter/lactation/.
- ↑ 7.0 7.1 Physiology, Fetal and Neonatal (2024-03-22). "Drug Transfer During Breastfeeding" (in en-US). https://clinicalpub.com/drug-transfer-during-breastfeeding/.
- ↑ "NDC | Lactogenesis: secretory differentiation and activation of the human mammary gland". https://ndcinstitute.au/article/d9d9a92d-471b-4c1b-80de-bdc49cc3fc5f/lactogenesis-secretory-differentiation-and-activation-of-the-human-mammary-gland.
- ↑ "NDC | Limitations of the bioactive factors Feedback Inhibitor of Lactation model". https://ndcinstitute.au/article/781aa171-6c68-49b5-ab73-ae372fa0769b/limitations-of-the-bioactive-factors-feedback-inhibitor-of-lactation-model.
- ↑ Peaker, M.; Wilde, C. J. (July 1996). "Feedback control of milk secretion from milk". Journal of Mammary Gland Biology and Neoplasia 1 (3): 307–315. doi:. ISSN 1083-3021. PMID 10887504.