An improved method for preserving the cellular membrane ultrastructure of in vitro cultivated cells using tannic acid.

Treatment of cultured cells with tannic acid after fixation with glutaraldehyde and osmification prevents the ultrastructural deterioration of cellular structures during dehydration and impregnation. Membranes of tannic acid-treated cells showed an increased contrast and sharp delineation of the polar zone. These results are discussed on the basis of simultaneous interactions of tannic acid with saturated phospholipids and OSO4. No ultrastructural differences are found between cells treated with tannic acids of different molecular weights.