Fig. 2.

Schematic representation of the relative distribution of epithelial (EpCAM⁺) cell types within the smaller E18.5 fetal and virgin female adult mammary gland (i.e., excluding stromal cells, endothelial cells and blood cells). The smaller fetal gland is artificially enlarged here by ~5-fold. In both the fetal and adult mammary gland, the MRU content is smaller than the CFC content, shown here as separate entities, recognizing that they may overlap to some extent. However, the proportion of all epithelial cells that are detectable as CFCs (in 2D assays) or MRUs (in transplantation assays) is higher in the fetal gland than in the adult gland