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RESEARCH PRODUCT

Histochemistry of the Mitochondrial System

subject

description

It has been customary to introduce any discussion on the mitochondrion by summing up its functions as the energy center of the cell. Because of the extensive reviews and symposia in this field in recent years such an introduction would be repetitious and will therefore be omitted. — The relative ease by which mitochondria can be isolated from various cells and the considerable purity of such fractions permitted an analysis of the overall functions of mitochondria and the extrapolation of these results, on a statistical basis, to a single mitochondrion. Further fragmentation of isolated mitochondria into sub-units that carry segments of the functional activity of the whole organelle significantly contributed to the understanding of this complex system. With the discovery of morphologic sub-units, using high resolution electron microscopic techniques, a stage is approached where the inextricable connection between structure and function becomes a tangible reality rather than a cliche, so widely used by biologists. — Concentration on the basic aspects of mitochondrial organization and the ingenuity and industriousness by which this approach is pursued have somewhat diverted our attention from problems faced at a higher level of organization. I am referring to such questions as the origin and fate of individual mitochondria, structural and biochemical variations within a cell and in various cells in an organ, intracellular interactions of mitochondria with other cell organelles, or in other words, the problems in which mitochondria with their structural and morphologic facets are viewed from cell and organ physiologic points of view. Here the potentialities of in situ techniques, including histochemical staining methods, are obvious. — The program of this symposium intends to reflect the two levels of operation at which investigations of mitochondrial systems are pursued. One refers to the basic problem of molecular organization. The other approach, including the use of histochemical techniques, is not refined at present to a molecular level of organization, but it nevertheless offers other parameters for the understanding of the biology of mitochondria. — In the followings Dr. Andre will discuss the general morphology of mitochondria. Dr. Stoeckenius will review the evidence for the existence of morphologic sub-units. Dr. Siebert will focus on some biochemical aspects of mitochondria structure. Drs. Bahr and Zeitler will deal with the problems of origin and fate of mitochondria, in general, while Dr. Luck will present evidence indicating that mitochondrial populations increase by division of existing mitochondria and that the mitochondrial mass is augmented by addition of new units to the existing frame-work. Drs. Farber and Morrison’s and Dr. Barrnett’s talks should provide us with the critical understanding of the potentialities of the in situ staining techniques. Finally, Dr. Balogh assumed the difficult task of discussing how histochemical technics may contribute to the investigation of organ physiologic problems.