Ultrastructure and fatty acid composition of fatty acid-modified Morris 7777 hepatoma cells

Morris 7777 hepatoma cells, maintained in culture for 5 days in Lewis medium supplemented with 0.1 to 0.35 mM cis-unsaturated fatty acid of the oleic (number of carbon atoms: number of double bonds, 18:1), linoleic (18:2), or arachidonic (20:4) type, were compared to similarly maintained, unsupplemented cells as to ultrastructure and fatty acid composition. The cells of unsupplemented cultures were distinguished by their spherical shape, multilobated nuclei, large nucleoli, and distribution of chromatin. Cellular extensions in the form of pseudopodia and filopodia along with junctional complexes and structures resembling bile canaliculi were evident. The cytoplasmic matrix and cellular organelles appeared normal in morphology. The ultrastructure of fatty acid-supplemented cells differed from unsupplemented hepatoma cells in cell size, location of the nucleus, abundance of endoplasmic reticulum, accumulation of lipid droplets, mitochondrial abnormalities, redistribution of cytoplasmic fibrils, and plasmalemmal extensions. Supplemented cells contained lipid droplets varying in number from a optimum of six to a maximum of greater than 70. The size of these lipid droplets varied from 0.57 +/- 0.34 (S.D.) micrometers for oleic, 1.22 +/- 0.67 micrometers for linoleic, and 0.91 +/- 0.46 micrometers for arachidonic acid-supplemented cells. Variation in the ultrastructure of supplemented cells was also evident. Cytoplasmic vesiculation appeared more frequently and was more prominent in the linoleic acid-supplemented cells. Alterations in the number of surface specializations and nuclear morphology were more pronounced in the arachidonic acid-supplemented cells. Occasional swelling, loss of matrix density, and dilated cristae were evident in mitochondria of oleic acid-supplemented cells. The neutral and phospholipid fractions of arachidonic acid-supplemented cells differed from the unsupplemented cells in the concentrations of 14:0, 15:0, 16:0, 16:1, 17:0, 18:0, 18:1, 18:2, 20:1, 20:3, 20:4, 22:5, and 22:6 fatty acids. The most significant change was detected in the higher level, 26- or 8-fold, of fatty acids 20:3 omega 6 and 22:6 in the phospholipid fraction of arachidonic acid-supplemented cells.