MITOCHONDRIAL CHANGES IN DIFFERENT 

 PHYSIOLOGICAL STATES 



Edward W. Dempsey 



Department of Anatomy, Washington University Medical School, St. Louis, 



Missouri 



Mitochondria, denned by light microscopy as organelles 

 stainable by selective stains and intravitally by Janus green, 

 have been identified in sections examined with the electron 

 microscope. They appear after osmic fixation as ovoid or 

 elongated structures with an outer limiting membrane. 

 This membrane is a double one. Its inner lamina is folded or 

 extended into many inward projecting folds, each of which 

 is composed of two closely apposed membranes. Enclosed 

 by the limiting membrane and between the inner folds is 

 a homogeneous, moderately dense matrix, in which there 

 occurs occasional dark granules. The number and complexity 

 of the internal laminar folds, the density of the matrix and 

 the size and number of the granules all exhibit variations from 

 tissue to tissue, but are reasonably similar from cell to cell in 

 the same tissue. 



We have examined mitochondria from several tissues in 

 different physiological states, or after various experimental 

 procedures. These organelles prove easily susceptible to 

 alteration. They swell rapidly if fixation is delayed after 

 the death of the animal. This post-mortem swelling can be 

 prevented, however, by subjection to hypertonic solutions. 

 Mitochondria behave, therefore, somewhat like osmometers. 



After intravital exposure to several foreign or toxic reagents, 

 mitochondria appear to concentrate the foreign substances 

 and to become altered in the process. In rats, to whose 

 drinking water silver nitrate had been added for long periods 

 of time, deposits of dense granules occurred in basement 

 membranes and in macrophages throughout the body and, 



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