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TISSUE RECONSTRUCTION 

 FROM DISSOCIATED CELLS* 



Aaron A, Moscona 



UNIVERSITY OF CHICAGO 



One of the characteristic features of embryonic development is that, 

 throughout its course, cells and cell groups are frequently in motion, 

 shifting positions or moving to new sites. Cells leave their places of 

 origin and move— individually or in swarms— by migrating through 

 tissues or by way of the blood stream to new, specific areas; there they 

 reunite, regroup, and, by interacting with other cells, form new 

 functional entities. Their movements and associations arise as if in 

 response to highly specific signals and means of recognition; their col- 

 lective activities provide the blueprints and the frameworks for the 

 structural and functional shaping of tissues and organs. Though these 

 cell maneuvers and the developmental processes tied in with them are 

 one of the main themes of embryology, relatively little is known about 

 such activities at the cellular level, and even less about the operational 

 laws basically involved in the grouping, association, and ordering of 

 cells into histogenetic systems. By tradition and for technical reasons, 

 embryologists have long been concerned with "potentialities" of rather 

 complex, multicellular parts of the embryo, with tissues, regions, and 

 organ-rudiments. The characteristics displayed by such cell masses are 

 obviously composite effects, in that they reflect the functions of diverse 

 constituents and do not readily permit a clear distinction between the 

 properties of units and of groups. More recently, interest has been shift- 

 ing toward the opposite end of the structural scale— toward various sub- 

 cellular and molecular aspects of embryonic systems— in a quest for 

 chemical answers to the problems of development. 



" Most of the author's work reported here has been aided by grants from the 

 National Cancer Institute and the Dr. Wallace C. and Clara A. Abbott Fund of the 

 University of Chicago. 



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