Influence of membrane active substances on cell surface morphology of cultured aortic endothelial cells.

1. The changes occurring on the surface of cultured aortic endothelial cells under the influence of exogenous cholesterol, lysolecithin, or cholesterol + lysolecithin were pursued by scanning and transmission electron microscopy. 2. Both compounds were found to cause surface changes under different quantitative relations, as shown by scanning electron microscopy of unfixed preparations. The changes were less significant in preparations fixed prior to the scanning--or transmission electron microscopic examination. 3. Other cell lines maintained in this laboratory and similarly treated with cholesterol, were found to be less responsive than the endothelial cells. 4. Cholesterol content was determined by thin layer chromatography in six different cell lines, before and after the addition of cholesterol. Only the endothelial cells showed a notable rise of cholesterol content after treatment. This fact may confirm our finding that cholesterol induced morphological changes were demonstrable only in the endothelial cells.