Influence of ovariectomy on mouse mammary epithelial cell subpopulations. (A) Flow cytometric analysis showing the distribution of epithelial and non-epithelial cell types from control and ovariectomised (Ovx) mice. (B) Bar chart depicting total epithelial cell numbers in control and Ovx mice. (C) Proportion of epithelial cell populations in control and Ovx mice. (D) Total colony-forming cell (CFC) numbers in control and Ovx mice. (E) Size of colonies generated from oestrogen receptor-negative (ER-) and oestrogen receptor-positive (ER+) progenitors isolated from control and Ovx mice. Right panels: CFCs of a representative experiment. Error bars indicate the standard error of the mean for four independent experiments. *P < 0.05, **P < 0.01, ***P < 0.0001. EpCAM, epithelial cell adhesion molecule; NCL, nonclonogenic luminal.