Human blood cell reconstitution in humanized mice. NOD/SCID or NSG mice (n = 50) were transplanted with human CD34⁺ cells alone (n = 29) or along with human fetal thymus tissue (n = 21). (A) Levels of human CD45⁺ cells, CD3⁺ T cells, and CD19⁺ B cells in PBMCs, as well as human CD235a⁺ RBCs in whole blood were analyzed by flow cytometry between 9 and 38 weeks after human cell/tissue transplantation. Each symbol represents an individual mouse. (B) Flow cytometric profiles of humanized mouse PBMCs stained with anti–human CD45 and anti–mouse CD45, and RBCs stained with anti–human CD235a and anti–mouse Ter119.