Primary MECs display limited proliferation potential in 2D culture.

<p>(a) MECs were isolated from pregnant mice and plated onto collagen I coated coverslips in complete media. (i) The percentage of proliferating cells was determined by EdU incorporation on each day for 6-d after isolation. Statistical significance determined by ANOVA is indicated: *** = p<0.001. (ii) Cells were co-stained with keratin 5 to detect the myoepithelial cells. Scale bar: 13 µm. (b) MECs from pregnancy days 12–14 (mid-grey) and 10 week old virgin (light-grey) mice were isolated and treated as above, and their proliferation compared to the cells isolated at pregnancy days 16–18 (black) by EdU incorporation. There were no significant differences in proliferation between MECs from ducts and alveoli within each time point (not shown on the graph).