Delineating the Epithelial Hierarchy in theMouse Mammary Gland

摘要

Reconstitution assays have shown that mouse mammary stem cells reside within the mature mammary gland in vivo. Singlecells could be prospectively isolated and shown to regenerate an entire mammary gland that exhibited full developmentalcapacity. The more recent identification of luminal progenitor populations has indicated that the mammary epithelium is orga-nized in a hierarchical manner. Further definition of epithelial cell types in both mouse and human mammary glands will pro-vide insight into the "cells of origin" in the different subtypes of breast cancer, as well as the nature of cancer-propagatingcells. Here, we review the known characteristics of mammary stem and progenitor cells, their steroid receptor status, and thepathways that have thus far been implicated in regulating their self-renewal and differentiation.