Ribosomes and Secretory Granules in Human Mast Cells: Close Associations Demonstrated by Staining with a Chelating Agent

The distribution of ribosomes was investigated in mature human mast cells with a chelation-based staining protocol known to bleach DNA-rich structures, leaving RNA-rich structures unbleached. With this method, electron-dense ribosomes were adjacent to, attached to, and within secretory granules, which were also bleached with the chelation method that we used. The finding of these ribosome-secretory granule relationships suggests that secretory granules in mature human mast cells may participate in RNA metabolism.