CROSS STRIATED MUSCLE IN TISSUE CULTURES 189 



Champy, in a sei'ies of articles, has maintained that most of 

 the cells in the body dedifferentiate in tissue cultures. They re- 

 turn, he claims, to a completely indifferent type of cell that no 

 longer shows the imprint of its origin. In explants from late 

 fetal stages he finds that cells of the kidney tubules, of the thyroid, 

 of the parotid and of the submaxillary glands, of the smooth 

 muscle, of the mesenchyme, etc. dedifferentiate into an indifferent 

 embryonic type indistinguishable from each other. This dediffer- 

 entiation, he claims, is associated with the phenomena of cell 

 division. 



The rapidity of dedifferentiation is a function of the rapid- 

 ity of the cell-division. Furthermore, according to Champy, 

 all cells differentiated for a special function lose or tend to lose 

 during mitosis, their characteristic function. In the animal 

 organism they recover immediately after the telephase, since 

 they are subject to the same functional excitation as before 

 division. In the body, function does not maintain the differ- 

 entiation but the function provokes and creates anew the dif- 

 ferentiation after each mitosis. Champy's ideas are based in 

 part on a law formulated by Prenant that a ceU during mitosis 

 does not secrete. Among the tissues which do not dedifferen- 

 tiate he finds the liver cells of the rabbit near term, the true 

 gray substance of the central nervous system and striated 

 muscle. Such tissues he finds do not grow out into his cultures 

 and he reasons that since they do not grow and vegetate they 

 are not susceptible of dedifferentiation. Maximow, on the 

 other hand, takes exception to Champy. He finds that fibro- 

 blasts continue indefinitely as such through many generations 

 of the culture and for this reason he calls them 'immortal* 

 cells. Maximow also finds that the endothelial cells of blood 

 vessels and of lymphatics as well as the mesothelial cells lining 

 the serous ca\dties change into fibroblasts and become indis- 

 tinguishable from those of connective tissue origin. This de- 

 differentiation is according to Maximow only apparent since he 

 considers the endotheUum of blood vessels and lymphatics and 

 the serosa but flattened-out fibroblasts. 



