Expression of L-selectin among primitive bone marrow and thymic progenitors. Representative expression of L-selectin and c-kit on Lin^Neg Sca-1^Pos mouse bone marrow (A-B) and CD4^- CD8^- thymus cells (C). For bone marrow statistics, percentages were averaged from 9 separate sorting experiments representing marrow pooled from 68 total donor mice. Thymic statistics represent 9 separate mouse thymuses. In all cases, error indicates SEM.