Gap junctions between cells of bone marrow: an ultrastructural study using tannic acid.

In bone marrow of the mouse perfused with fixative containing tannic acid and glutaraldehyde, gap junctions were observed between certain cell types. Gap junctions were seen between adjacent reticular cells, between adjacent macrophages, and between macrophages and reticular cells. Macrophages formed gap junctions with immature neutrophils, eosinophils, monocytes, and erythroblasts. Often a single macrophage had gap junctions with neutrophilic, eosinophilic, and monocytic cells; these blood cells varied from immature to nearly mature forms. In contrast, the macrophages associated with erythroblasts had gap junctions only with erythroblasts and all the erythroblasts were in the same developmental stage. The possible role of the gap junctions in differentiation and mobilization of marrow cells is discussed.