Under pathological conditions histiocytes, which are cells generally lacking any membrane interconnecting elements, may acquire the ability to form desmosome-like junctions. Coated vesicles appear to play an important role in this process. The small coated vesicles released from the Golgi apparatus would apparently migrate toward the surface of the cell and fuse with the plasma membrane, releasing their contents to the outer surface of the cell. The coat of the vesicles would form an area of dense material on the inner surface of the plasma membrane. Microfilaments of approximately 70 Å in diameter become associated with these plaques. When a homologous cell aligns, a granular material sometimes exhibiting a central dense layer appears in the intercellular space. Membrane interconnecting elements would thus be formed, morphologically quite similar to the desmosomes present between epithelial cells but with a higher diameter (exceeding 580 Å) and an associated filament system of approximately 70 Å in diameter (70 F maculae adherens). © 1979 Academic Press, Inc.
