Flat embedding and immunolabelling of SW 1116 colon carcinoma cells in LR white: An improved technique in light and electron microscopy

Human SW 1116 colon carcinoma cells were grown on matrixcovered coverslips and flat embedded in specially prepared gelatin capsules in the hydrophylic resin LR White. Dehydration and polymerization were carried out so as to maximize preservation of antigenicity. Sections were cut perpendicular to the substratum. To visualize mucin, semithin sections of SW 1116 cells were stained with periodic acid Schiff (PAS) reagent for light microscopy, and ultrathin sections were labelled with a monoclonal mucin antibody (Mab 199) and immunogold for electron microscopy. Immunofluorescence was carried out on whole cultured cells using Mab 199. The morphological preservation of SW 1116 cells embedded in LR White was comparable to that of Eponembedded cells. Mucin was localized on the microvillar surface of the apical plasma membrane and occasionally in intercellular spaces between adjacent cells. Mucin was also present in vesicles in the apical and lateral part, and to a lesser extent in the basal part of the cells. We conclude that this new technology significantly improves the morphological preservation of cells and tissues in LR White, while also serving to sustain the antigenicity of cellular antigens. Copyright1992 WileyLiss, Inc.