Abstract
Observations with the electron microscope were made on hepatic parenchymal cells of rats which had received an intraperitoneal injection of crystalline papain protease 48 hours before sacrifice. Most of the cells appeared dark due to a more compact arrangement of the various cytoplasmic organelles, which retained their normal organization. Occasionally, slight changes were observed in some of the organelles. The striking mitotic activity induced by papain protease seems to be due to a direct action of the enzyme rather than due to compensatory hyperplasia following damage to the liver tissue.
