Agrin is expressed by osteoblast at the hematopoietic niche. (A) Confocal images of methapyseal sections of leg bones obtained from control mice and stained for osteopontin (red), agrin (green) and nuclear DNA (blue). Scale bar, 40 μm; inset scale bar, 20 μm. (B) Z-stack projection of 26 BM confocal sections (0.5 μm each) of trabecular bones obtained from control and Musk-L;Agrn^−/− mice stained for osteopontin (red), agrin (green), and nuclear DNA (blue). Scale bar, 20 μm. (C) Osteopontin-positive cells enzymatically isolated from long bones of control mice and stained for osteopontin (red), agrin (green) and nuclear DNA (blue; top row) or osteocalcin (red), agrin (green), and nuclear DNA (blue; bottom row). Scale bar, 50 μm.