Why do crystalline precipitates in plasma cells always coalesce with parallel light and dark lines strictly...

During transmission electron microscopy of plasma cells from two patients with plasma cell proliferative disorders, we observed a large number of small crystals, most of which showed a striation with alternating light and dark parallel lines. Ultraphotos strongly suggested that smaller crystals often coalesced to larger ones. The coalescence occurred in such a way that the parallel lines of the respective smaller crystals always met each other end-to-end and hardly ever end-to-side. A similar pattern can be seen on previously published ultraphotos from other patients with plasma cell proliferative disorders and intracellular crystals, although not commented upon by the respective authors. The parallel lines of the smaller crystals certainly must correspond to defined structures of the crystal. The stability of a certain configuration is therefore in all likelihood due to electrical potentials created by the crystal structure.