Figure 1. Primary cultures of leiomyoma cells after incubation with different concentrations of progesterone Photographs showing the effect of progesterone 0.01μg/ml (b), 0.1μg/ml (c) and 1μg/ml (d) on leiomyoma cell cultures after 72 h of treatment. Cells incubated only in culture medium were used as controls (a). Photographs were taken with a phase-contrast microscope (50x magnification).