F. ISOLATION OF CYTOPLASMIC 

 PARTICULATES 



A. MITOCHONDRIA 



The mitochondria, dispersed throughout the cytoplasm of cells, are 

 microscopically visible and have been known for some time. How- 

 ever, their isolation was not accomplished until 1934 when Bensley 

 and Hoerr succeeded in separating them from liver cells of the guinea 

 pig by differential centrifugation. The substantial gap in time be- 

 tween the recognition of mitochondria as structural entities in the 

 cytoplasm, and their isolation, was largely due to their highly labile 

 character, at least in cells of some animals. Mitochondria rapidly 

 disappear from the cells after death, and they also disappear when 

 tissue is treated with organic solvents or fluids containing appreciable 

 acetic acid, and when the temperature is elevated to 48-50°. An 

 exception has been found, in the case of mitochondria of the liver 

 cell of Amblystoma, by Bensley and Gersh (1933b), who observed 

 that, after freezing-drying the tissue, extraction with organic 

 solvents, treatment with acetic acid, or elevation of temperature 

 did not cause the disappearance of these bodies. The particles called 

 "secretory granules" by Claude (1943a) include mitochondria. 

 Subsequently Claude (1946) referred to particles from liver cells of 

 0.5-2.0 IX diameter as "large granules" which consist "of secretory 

 granules and mitochondria." Some additional details for the isolation 

 procedure of Bensley and Hoerr (1934) have been given by Hoerr 



(1943) and are incorporated in the following description. Claude 



(1944) and Claude and Fullam (1945) employed certain neoplastic 

 cells of the rat as a source of mitochondria, and Claude (1946) gave 

 a detailed description of the separation of particulates from liver.* 



Bensley and Hoerr Procedure for Guinea Pig Liver 



The entire procedure should be carried out in a cold room at 0°. 



Remove blood from the liver by perfusion with cold 0.85% sodium 



* Since this writing, Hogeboom et al. published a paper on the isolation of 

 mitochondria from rat liver; see Bibliography Appendix, Ref. 55. 



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