C H A P T E R
1 4
Recombination of Dissociated Cells
and the Development of Cell Aggregates
A . A . M O S C O N A
Department of Z
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°l°gy> University of Chicago,
Chicago, U.S.A.
I. Introduction
489
II. Aggregation of Cells
490
A. General
490
B. Self-aggregation
492
C. Mediated aggregation
494
D. Extrinsic factors in rotation-mediated aggregation
498
E. Cellular factors in rotation-mediated aggregation
501
III. The Development of Aggregates
505
A. General
5
B. Development of isotypic cell aggregates
507
C. Development in heterotypic cell aggregates
516
IV. Remarks on the Internal Patterns of Aggregates
519
References
524
I. I N T R O D U C T I O N
In recent years it has been found that cells dissociated from various
embryonic tissues or organ rudiments, when maintained under
suitable in vitro conditions tend to aggregate and reestablish multicellular, tissue-like structures. Restitution of tissues from individual cells
in suspension can be performed under conditions essential for exact
work; judiciously employed, the phenomenon of cell aggregation lends
itself effectively to studies, at the cellular and molecular levels, of processes and factors involved in the mutual attachment of cells and their
organization into developmental systems. Classical "cell culture" and
"organ culture" methods investigate the properties in vitro of dispersed
cells and of whole tissue fragments, respectively; the methodology of
cell aggregation is concerned with the transition, under stated experimental conditions, from uni- to multi-cellularity; it aims to define the
differences in performance of separated cells versus grouped cells and
to characterize specifically the various factors intrinsic and extrinsic to