DN1 CD122⁻NK1.1⁻ thymocytes differentiate into NK1.1⁺ cells with a unique phenotype. DN1 CD122⁻NK1.1⁻ thymocytes from Rag1^−/− Ly5.2 mice were transferred into irradiated Rag1^−/− Ly5.1 mice intrathymically. Donor (Ly5.2⁺) NK cells from IT mice were compared with NK cells from unmanipulated (nonirradiated) littermates 32 days after transfer. Gray-filled histograms represent cells stained with an isotype control and black-line histograms represent cells stained with the indicated antibody. Although the staining patterns for each marker were somewhat different, even for the same marker on different cell populations, ie, some markers were expressed on all cells while others were expressed on subsets, we used the percent of positive cells (above isotype control staining) as a convenient (although technically imprecise) means to compare and describe the staining profiles for a large number of markers. Data are representative of 2 experiments.