Histomorphometrical method used to determine acinar and ductal wall thickness in cultured human breast explants. The areas outlined in black represent the measured sector of acini (A) and ducts (B). Columns represent the mean counts ± SD. Asterisks indicate the statistical significance of differences between control and treatment groups (*, p < 0.05; **, p < 0.01) and NS, not significant. The differences between treatment groups E2 vs. E2+MPA, E2 vs. MPA and MPA vs. E2+MPA did not reach statistical significance at any day of organ culture. (H&E staining. Scale bar 100 μm).