Polysomes of eukaryotic cells observed by electron microscopy

Shapes of polysomes of eukaryotic cells were determined by surface spreadin g of cells. We examined unicellular protozoan Tetrahymena cells, rabbit ret iculocytes, and cultured MDCK, BHK and HeLa cells. Polysomes had ring-, 8- and caterpillar-shaped forms, indicating that eukaryotic cells contain fund amentally circular polysomes. Isolated and partially purified polysomes fro m Tetrahymena cells had features of polysomes similar to those of spread ce lls. These findings indicate that circular polysomes are not an effect of t he spreading, but are actual features of the cells.