Stem Cells and Cellular Origins of Mammary Gland: Updates in Rationale, Controversies, and Cancer Relevance

Figure 1

(a) The postnatal mammary gland development is multistage. (b) Two distinct phenotypes of mammary epithelium in different developmental stages: the ductal (A) and alveolar (B) epithelium, both bilayered, with inner layer of luminal cells and outer layer of myoepithelial/basal cells. There are also milk-producing cells in the inner layer of alveolar epithelium.

(a)

(b)