Additional characteristics of Lin⁻TdT⁺ bone marrow cells.

Sorted Lin⁻ bone marrow cells were stained for surface antigens followed by intracellular TdT staining and analysis by 4 parameter flow cytometry (described in “Materials and methods”). The Lin⁻ TdT⁺ cells in each panel are shown as black dots, whereas all remaining cells are shown as yellow dots. Percentages of the total population of Lin⁻TdT⁺ cells in each quadrant are also given. Cells were also stained for the Ki-67 proliferation antigen (bottom panel). Expression of Ki-67 in Lin⁻ TdT⁺ cells (bold) was compared with that in Gr-1^Lo bone marrow cells (dotted) and in IgM⁺ B cells (plain) along with the isotype control (tinted).