BM remodeling and osteoblast morphology after hematopoietic cell depletion and TBI. (A) Hematoxylin and eosin (H&E)–stained and GFP-stained sections (40×) of metaphyseal BM 48 hours after both DT depletion and TBI in CD45Cre^– (control) and CD45Cre⁺-depleted mice demonstrating depletion of hematopoietic cells and alterations in osteoblast (OB) thickness. (B) Quantitative analysis of osteoblast thickness (n ≥ 5) after DT injection only, TBI only, or DT injection and TBI in mice expressing iDTR with and without the presence of CD45Cre cells. Results show a significant decrease in osteoblast thickness (3.42 ± 0.11 μm vs WT, 8.45 ± 0.31 μm; P < .0001) between mice treated with DT and TBI in the CD45Cre⁺ cohort. There was also a significant decrease between CD45Cre^– and CD45Cre⁺ mice treated with DT injection only (4.60 ± 0.23 μm in CD45Cre^– vs 2.89 ± 0.13 μm in CD45Cre⁺; P < .0001). (C) H&E-stained and GFP-stained sections (40×) of metaphyseal BM 48 hours after DT injection and TBI in Vav1Cre^– (control) and Vav1Cre⁺-depleted mice (n ≥ 5). (D) Analysis of osteoblast thickness in Vav1 depletion model confirming osteoblast flattening (4.55 ± 0.08 μm vs WT, 7.16 ± 0.43 μm; P < .0001).