SRGN^–/– mice have smaller MKs, increased PF4, and altered basement membrane protein levels. (A) Representative images of femur bone marrow from mice (aged 52 weeks). PF4 (cyan), Laminin (purple), CD41 (yellow), and DAPI (blue). The scale bar represents 20 μm. (B) MK size as determined by the size of CD41 stained cells. Bones from 9 individual mice were evaluated per group. The data shown are representative of the distribution of individual cell areas from each animal (WT, n = 2050; SRGN^–/–, n = 2901). (C) Quantification of PF4 fluorescence intensity normalized to background fluorescence within each image and displayed as a ratio to WT average intensity. Each point represents an individual mouse (n = 9). (D) Quantification of laminin fluorescence intensity normalized to background fluorescence within each image and displayed as a ratio to WT average intensity. Each point represents an individual mouse (n = 9). (E) Representative images of femur bone marrow from mice (aged 52 weeks). Collagen I (purple), CD41 (yellow), and DAPI (blue). The scale bar represents 20 μm. (F) Quantification of collagen I–positive area within each image in panel F. Each point represents an individual mouse (n = 9). Significance: ns is indicated by P > .05; ∗P ≤ .05; ∗∗P ≤ .01; ∗∗∗P ≤ .001; ∗∗∗∗P ≤ .0001. All error bars represent the SEM.