Identification of CD34⁺CD44^brightCD5^lo/−CD33⁻intermediate thymocytes in vivo. Lin⁻thymocytes depleted of the most immature CD34^int-bright precursors, as described in the Materials and Methods, were analyzed by flow cytometry for the correlated expression of CD44, CD34, and one of the indicated MoAbs. Electronic gates were set as shown in the upper biparametric plot to analyze either the cell size (mean forward scatter, FSC) or the expression of CD5, CD13, and CD33 antigens (shaded histograms) on CD34⁺CD44^bright (gate I) and CD34⁺CD44^lo/− (gate II) thymocytes. Background staining values (unshaded histograms) were determined with isotype-matched irrelevant antibodies.