Silver staining of nucleolar granules in tumor cells

With the aid of a simple silver-staining procedure, large numbers and unusual arrays of nucleolar argyrophilic granules were found in Novikoff hepatoma, KB, and HeLa cells. Some of these arrays consisted of linearly arranged discrete granules, and others were in two to three rows each containing three to five granules. Corresponding formations were not found in either the normal or regenerating liver nucleoli which contained an argyrophilic network in which the dark granules were apparently associated with the less dark argyrophilic fibrils of a reticulum. The nucleolar argyrophilic granules were readily identifiable in the separated daughter nuclei of the tumor cells in telophase, suggesting that the increased nucleolar activity of the G1 phase begins in these cells even before cell division has been completed.