Immunostained BM sections from BCR/FGFR1, ZMYM2/FGFR1, and MIG NOD/SCID mice. (A) BCR/FGFR1 and ZMYM2/FGFR1 mice display increased levels of human granulocytic and erythroid cells in BM as shown by immunostaining for MPO and CD235a. BM sections from a representative MIG mouse reveal single granulocytic and erythroid human cells staining positive for MPO and CD235a. (B) Human cells in BCR/FGFR1 and ZMYM2/FGFR1 mice BM also differentiated into macrophages and mast cells as shown by morphology and positive staining for CD68 and CD117 in BM sections from representative mice. Typically, macrophages and mast cells formed round clusters of cells. In MIG mice, only few cells stained positive for CD68 or CD117. (C) In BM sections from BCR/FGFR1 and ZMYM2/FGFR1 mice, as well as from MIG mice, dispersed B-lymphoid cells, staining positive for CD20 were found, whereas T-lymphoid cells positive for CD3 were more rarely detected. (D) In BCR/FGFR1 mice, human granulocytopoiesis frequently displayed a left-shifted maturation pattern with eosinophilia, as shown by morphology in HE stained sections and immunostaining for MPO (top panel). Furthermore, accumulation of erythroid blasts as shown in HE stained sections and by CD235a staining was observed (bottom panel).