Histopathology of mice receiving transplants of FLT3-ITD–transduced bone marrow.

(A) Peripheral blood smear (Wright-Giemsa stain, original magnification × 400) from a representative FLT3-ITD mouse (mouse 51.1) reveals marked leukocytosis comprised predominantly of maturing myeloid elements. (B) Bone marrow from the femur of the same mouse (hematoxylin and eosin, original magnification × 500) reveals features of a myeloproliferative disorder with marked hypercellularity and myeloid hyperplasia consisting predominantly of mature granulocytic elements. Spleen (C) and liver (D) (hematoxylin and eosin, original magnification, × 500) also reveal an identical myeloid infiltrate in the Flt3-ITD mouse (mouse 51.1). (E) Bone marrow of a Flt3-ITD mouse (mouse 78.5) and (F) bone marrow from a wild-type FLT3 mouse. Both were stained to highlight reticulin fibers (black) (original magnification, × 500). There is a marked increase in reticulin fibrosis in the FLT3-ITD mice compared to wild-type FLT3 mice.