2 SUBCELLULAR PARTICLES 



PHASE CONTRAST MICROSCOPY APPLIED TO LIVING AND SURVIVING CELLS 



Our survey of techniques of biochemical cytology naturally begins with the 

 living cell. The tissue culture cells virtually speak for themselves in the excellent 

 motion pictures taken with the phase-contrast microscope or interference micro- 

 scope. Among the films we have seen are those of Dr. Gey, showing remarkable 

 mitochondrial movement, cell membrane activity and pinocytosis ( 14); Dr. Biesele, 

 showing the speeding of mitochondrial movement by coenzyme A addition and 

 the accentuation of the tendency of mitochondria in the mouse fibroblasts to join 

 end to end (55);" Drs. Frederic and Chevremont, showing the dramatic changes 

 in mitochondria induced by a variety of drugs (6); Dr. Rose, showing the re- 

 markable transformations of pinocytosis vacuoles in a variant of the HeLa 

 cell (45);" and Drs. Bloom and Zirkle, showing mitosis in amphibian fibroblasts, 

 with chromosomes and kinetochore evident as well as the extensive surface 

 bubbling at late anaphase and telophase. - 



Even tissue culture has a limitation we encounter with other techniques: it 

 reveals the capacities of the cultured cells, but perhaps not the actualities of these 

 cells in the organized structure of the multicellular organism. The specialized 

 milieu in which they are grown is quite ditTerent from that encountered naturally 

 by cells embedded in tissue mucopolysaccharide or wedged in tightly among 

 neighboring cells, as in epithelium — cells always under the controlling neural, 

 hormonal and neurohumoral influences of the organism. Thus, the chromosomal 

 changes which many cells in culture undergo so readily may occur very rarely 

 within the tissue. The very extensive pinocytosis or the surface bubbling at late 

 mitotic anaphase and telophase may be exaggerations of surface changes which 

 cells display in the organism. 



This in no way minimizes the importance of such films in emphasizing the 

 dynamic nature of the cell. They are balancing forces needed when we reflect 

 upon the static electron micrographs of mitochondria or of plasma membranes in 

 cells, or when we consider the biochemist's descriptions of the multi-enzyme 

 machinery of mitochondria, such as Dr. Green's brilliant description in this 

 volume (17) of the shuttling of small molecules within the lipoprotein matrix. 

 The description of the cell's constant dynamism in biochemical terms is the great 

 challenge for future biochemical cytologists. 



Phase-contrast micrography can be of great value to biochemists and others with- 

 out cinemaphotography equipment and even without truly living cells. I have in 

 mind examination of fractions isolated by differential centrifugation, or of surviv- 

 ing (or dying) cells, as in homogenates. 



In figures i and 2 are phase contrast photographs of cells in homogenates. It is 

 evident that in liver cells the mitochondria are large and numerous, while in cells 



- A short sequence from this hhn was shown at the Conference. I am grateful to the authors 

 for permission to show the film. 



