Overview of 3D reconstructions of mouse BM architecture. Using DIC (A), mouse marrow tissue within the bone fossae of the sternum was located and examined; corresponding z-series of immunofluorescence images (B) (approximate volume of 600 × 600 × 150 μm3) were reconstructed. (B) A 3D blend rendering showing large islands of CD45R+ cells (B lymphocytes in red), surrounded by extracellular matrix (perlecan in green), and DAPI (blue) identifying all nucleated cells. (C) A depth color coded 3D image where the depth was pseudocolored (0 μm = orange and 100 = magenta) of the same field as in panels A and B. The close-up 3D images either as maximum intensity (D) or as blend projection (E) display an intricate network of extracellular matrix (perlecan in green) outlining blood vessels and the nests of CD45R+ cells (B lymphocytes in red). DAPI (blue) identifies all nucleated cells (E). Related images appear in supplemental Video 2.