CD25 and CD44 expression in CD3⁻ and CD3^lo thymocytes in control or irradiated mice. Major quadrants: upper left, CD25⁻CD44⁺ cells; upper right, CD25^+(hi)CD44⁺ cells; lower left, CD25⁺CD44⁻ plus CD25ⁱⁿCD44⁻ (middle gate) cells; lower right; CD25⁺CD44⁻ cells. Numbers represent the percentage of thymocytes in each quadrant or the gate. Values were obtained with the labeling of pooled thymocytes from at least three animals per point.