Cytochemical Study of Mitochondrial Structure

Abstract

A CHARACTERISTIC morphological pattern of organization of mitochondrial structure has been repeatedly described by Palade¹, Sjöstrand², Rhodin³ and various other workers using electron microscope studies, according to which each mitochondria consists of a limiting membrane, cristæ and the mitochondrial matrix with granules or particles in it. During the cytochemical study of the oocytes of the various freshwater fishes, I^4,5 have defined a cytochemical pattern of mitochondrial structure. The mitochondria of the fish oocytes are granular filaments with uniform thread-like contour. Such a structure is revealed both vitally under phase-contrast microscope⁶ and cytochemically in the tissue prepared according to Baker's⁷ lipid preserving formaldehyde-calcium fixative. A similar structure is seen in the tissue fixed in osmium solution or osmium-containing fixatives, that is, Champy's and Lewitsky's (Flemming-without-acetic) fluids. However, their filamentous structure is completely destroyed in fat solvents or fixatives consisting fat solvents and strong acids, for example, Bouin and Carnoy's fluid, after which treatment their fine granules are observed to be randomly scattered in the cytoplasm. The mitochondrial filaments are coloured deep blue in sudan black B but this deep coloration is confined more rigidly at the periphery and at the interspaces between the fine granules of mitochondrial filaments. The granules in the mitochondria remain distinct by their feeble coloration in sudan black B. The peripheral sudanophil material is positive to Baker's⁷ acid-hæmatin technique revealing phospholipids, but is completely negative to all other lipid tests. Its exclusive lipid nature is further revealed by its negative reactions to Mazia's⁸ mercuric-bromophenol blue test for proteins, and by periodic acid-Schiff technique for carbohydrates. The granular component of mitochondria consist of abundant proteins, and in addition show some lipo-proteins revealed by Pearse's⁹ extractive technique. Thus the mitochondria structure consists of a basal phospholipid sheath, in which numerous protein granules are embedded.