Fig. 13. Primitive and committed cells in the cell cycle. Putative cardiac stem cells (arrows) expressing c-kit (green fluorescence in A) or MDR1 (purple fluorescence in B and C) on the surface membrane. These cell nuclei, stained by propidium iodide (blue fluorescence), are positive for Ki67 (yellow fluorescence in B) or MCM5 (white fluorescence in A and C). D and E illustrate in the same field a myocyte precursor positive for MDR1 (purple fluorescence in D and E; arrowheads), MEF2 (yellow fluorescence in D), Ki67 (white fluorescence E) and cardiac myosin heavy chain (red fluorescence in D and E; arrows). (Scale bars = 10 mm.) (F) Fractions of primitive and early committed cells in the myocardium. Results are mean ± SD. Asterisks indicate P < 0.001 between results in hypertrophied (AS) and control (C) hearts.