scid mutation does not affect HSC pools. BM cells from scid, Rag1^−/−, and WT mice were assayed by multiparameter FACS for proportion of HSC populations. At least 6 age-matched (8-10 weeks old) mice per genotype were compared. Representative FACS profiles of pregated on live, lineage negative cells, Sca1⁺, c-Kit⁺ (LSK) are shown in panel A, long-term HSCs (LSK, CD34⁻, Flk2⁻) and short-term HSCs (LSK, CD34⁻, Flk2⁺) are shown in panel C, and SLAM⁺ LSK (CD48⁻, CD150⁺,LSK) are shown in panel E. Frequencies of HSCs, LT-HSCs, ST-HSCs, and SLAM⁺LSK in BM from WT, scid, and Rag1^−/− mice are analyzed in panels B, D, and F. Error bars indicate SD; significance was determined by a Student 2-tailed t test.