Effect of triton X-100 on cytochemical and ultrastructural pattern of chromatin

The action of Triton X-100 on chromatin was observed in normal rat liver, thymus and ascites hepatoma cells. For DNA cytochemistry and thin-section electron microscopy the cells were treated with the permeabilizing 0.05% concentration of Triton 0.5-1% Triton treatment was applied to rat thymus nuclei spread on electron microscopic supports. Triton caused a compactness of chromatin in stained nuclei, in ultrathin sections and nuclear spreads. The most prominent feature of the tritonized higher order fibre is an increased regularity of its structure. In the nuclei stained for DNA with toluidine blue, Triton caused a sharp increase of optical density in the comparable zone of the spectral maximum and a shift to the shorter wave lengths. Cells treated with Triton exhibit an exaggerated anisotropic staining reaction. The cytochemical and cytophysical changes induced by Triton X-100 are explained by a polymerization caused by an increased regularity of the chromatin fibre structure.