Reduced B lymphopoiesis and abnormal myeloid differentiation and myelofibrosis in boo/boo mice. (A-B) Hematoxylin and eosin stain of spleen shows reduced white pulp and increased and disorganized red pulp with amorphous pink material in boo/boo mice. (C-D) Perl stain showing increased iron accumulation in red pulp macrophages within boo/boo spleen. (E-F) Increased reticulin (fibrosis) in boo/boo mice. (G-H) Absent B cells and relatively reduced T cells in boo/boo spleen. Numbers indicate percentage of cells falling within the indicated FACS gates. (I-J) Increased frequency of CD71⁺/TER119⁺ mature erythroid cells and also CD71^lo immature cells in boo/boo spleen. (K-L) Increased Gr1^hi neutrophils, Gr1^int monocytes, and TER119⁺ erythroid cells in boo/boo spleen. (M-N) Pie graphs show percentage contribution of B220⁺ B cells, CD3⁺ T cells, TER119⁺ erythroid cells, Gr1 bright granulocytes, Gr1 intermediate macrophages, and “other” cells (mostly CD71 weak early erythroid lineage cells) to the spleen. Numbers represent the mean of FACS analyses from 6 boo/boo mice and 6 wild-type (+/+) littermate controls.