Structural comparisons of cell organelles and nuclei in rat hepatocytes with three different fixation techniques

The morphological properties of cell organelles and nuclei in rat hepatocytes were compared, when the hepatocytes were either chemically fixed in glutaraldehyde and osmium (GA-Os), chemically fixed only in osmium (Os-2h) or physically fixed with a microwave-irradiated osmium (Mw-Os) fixative for a short duration. Judging from the fine structure, the mitochondria and rER were best preserved after physical fixation; because of the smooth surfaces and regular open contours, but both organelles shrank in the two chemical fixatives. The Golgi complexes and peroxisomes of the hepatocytes were not markedly changed by any of the fixative procedures. However the lysosomes and sER were changed to some extent after physical fixation. In the nucleus, the two kinds of chromatins and the nucleolus were best preserved with physical fixation. In conclusion, physical fixation is a very simple and fast procedure that is convenient for routine electron microscopy if some attention is paid to the morphological changes.