part of part of epithelial cell mammary gland epithelial cell 2010-09-20T01:49:37Z mammary epithelial cell An epithelial cell of the mammary gland. BTO:0004300 https://cellxgene.cziscience.com/cellguide/CL_0002327 Mammary gland epithelial cells, also known as mammary epithelial cells, are essential cell types in the tissue of mammary glands, which are milk-producing glands in female mammals. They can be categorized into two types: luminal epithelial cells and myoepithelial cells, each with their distinct functions in milk processing and delivery. Luminal epithelial cells, which are located in the inner layer of the mammary gland ducts and alveoli, play a vital role in the secretion of milk proteins and lipids to form milk during lactation. These cells contain well-developed secretory apparatus, including rough endoplasmic reticulum and Golgi complex, facilitating the synthesis and secretion of milk proteins. Luminal epithelial cells express markers, like cytokeratin 8 and 18, and hormone receptors, such as estrogen and progesterone receptors, which play a crucial role in regulating the cell proliferation during the mammary gland development and lactation. Myoepithelial cells, on the other hand, are contractile cells situated between the luminal epithelial cells and the basal lamina in the ducts and alveoli of the mammary gland. They express markers such as smooth muscle actin and p63. One of their chief functions is the contraction during lactation, which aids in the expulsion of milk from the alveoli into the ductal network. Additionally, myoepithelial cells play a role in shaping the mammary gland ductal system and initiating the involution process after weaning. The homeostasis and functionality of the mammary epithelial cells are sensitive to hormonal regulation and surrounding microenvironment cues. Any abnormalities in these two types of mammary epithelial cells could disrupt the mammary gland function and potentially prompt the development of breast diseases, including cancer. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) breast epithelial cell mammary gland