Presence of human leukemia cells on mouse bone marrow smear.

(A) Bone marrow smear from a mouse 6 weeks after injection with cells from a patient with T-ALL showing the characteristic morphology of leukemia blasts (arrowheads). (B) Bone marrow smear from a control NOD/SCID mouse showing the characteristic leukocytes. Bone marrow smears were stained with modified Wright stain.