Clonogenicity, expansion, and differentiation of SD cells. (A) Percent of cells that gave colonies after plating single cells into separate wells (1-3) of a 96-well microtiter plate. (B) Cumulative population doubling in medium containing 17% FCS as a function of passage number (p4 to p10). (C) Differentiation of SD cells into adipocytes (original magnification, × 10). Cells stained with Oil Red O. (D) Differentiation of SD cells into mineralizing cells (original magnification, × 10). Cells stained with Alizarin Red. (E) Differentiation of SD cells into chondrocytes (original magnification, × 40).