Fibulin-1 is deposited in the extracellular matrix surrounding osteoblasts in the frontal bone. Confocal microscopy in A, shows Fbln1 deposited in the ECM in wild-type mouse frontal bone (P0) (red). Panel A is derived from a collapsed z-series of multiple optical sections. Section of wild-type neonate (P0) skull in B, (containing frontal bone) is stained with H&E. Section of wild-type neonate (P0) skull C, is immunolabeled with antibodies to Fbln1 (red). The inset panel in C shows a higher magnification of the boxed region. Note that Fbln1 is deposited in the ECM around osteoblasts (arrowheads) located in the frontal bone. Nuclei in A and C were stained using Draq5 (blue). V, blood vessel; Cmc, condensed mesenchymal cells; D, dermis; FB, frontal bone; OB, osteoblast; OCy, osteocytes; OF, osteogenic front; TB, trabecular bone; TC, cell adjacent to trabecular bone.