Evidence for pluripotentiality by formation of multiple cell types at clonal cell densities. Sorted S⁻cells were plated at very low density (1,000 cells/100-mm diameter plate) and cultured for 45 days (A) × 4 magnification. Note the discrete, isolated colonies distributed througout the dish. Colonies were marked, observed over time, and found to arise from single cells. Colonies were stained for cartilage by alcian blue (B), for adipocytes by oil red (C) and for bone by von Kossa's reagent (D). (B) through (D) × 400 magnification.