Effects of BM-specific Rps6 hemizygosity on BM histology and cytology. (A) Representative histologic sections from animals of the indicated genotype; arrowheads indicate megakaryocytes, quantitated in panel B (n = 3 animals per genotype, mean number of megakaryocyte per hpf is shown ± SEM, 8 hpf per animal). (C) Immunofluorescence staining for VWF (green) in BM sections counterstained with DAPI (blue) from nonmutant and ribosomal protein mutant animals and quantitated in panel D (n = 3 animals per genotype, mean number of VWF-positive cells with large nuclei per hpf is shown ± SEM, 10 hpf per animal). (E) Cytospin preparations show increased numbers of immature erythroid (IE) cells and decreased numbers of mature erythroid (ME) cells in mutant compared with control samples. (F) Example of normal and abnormal (a monolobated micromegakaryocyte, arrowhead) megakaryocyte morphology in cytospin preparations from nonmutant and mutant BM, quantitated (G) as mean number of monolobated cells among 10 megakaryocytes evaluated per animal ± SEM (n = 4-5 animals per genotype). P values are based on a 2-tailed t test, *P < .05, **P < .01; NS indicates not significant. Scale bars: 50μM (A); 75μM (C); 20μM (E); 10μM (F).