Fig. 4. Phenotypical differences of muscle SP cells detected using varying Hoechst dye concentrations. Parallel samples stained with 5 µg ml^-1 (A) or with 12.5 µg ml^-1 (D) of Hoechst dye show different percentages of SP cells. As expected, the total percentage of CD45⁺ cells within the samples does not vary (B,E). However, when CD45⁺ cells are analyzed for Hoechst exclusion properties, 26% of CD45⁺ cells fall within the SP cell gate when the sample is stained with 5 µg ml^-1 of Hoechst dye (C), whereas no CD45⁺ cells are present in the SP gate when the sample is stained with 12.5 µg ml^-1 Hoechst dye (F).