CHAPTER 6
Cell Division
H. F I R K E T
Laboratoire d'Anatomie pathologique 3 Universite de Liege, Belgium
I. Introduction
203
II. Mitosis
4
A. General survey
204
B. Special aspects
206
III. The Cell Cycle
218
A. Duration of the cycle
218
B. Morphological changes
220
C. Metabolic changes (DNA cycle)
220
D. General considerations
225
E. Effect of ionizing radiations on the cell cycle
226
IV. Mitogenesis
227
V. Synchronism of Divisions in Cultures
229
V I . Conclusions
230
References
231
I. I N T R O D U C T I O N
Ever since tissues were first cultivated in vitro, cultures have constituted
one of the best biological objects for the study of cell division. They
combine various favourable conditions to an unusual extent: flattening
out of the cells enlarges the images of division as compared to more
compact tissues in the animal; observation on the living cells, which
is necessary to understand the variations—experimental or otherwise
— o f an essentially dynamic phenomenon, is particularly easy; cell
multiplication can occur at a high rate and in reproducible conditions;
cells used are similar to or even identical with those found in the
mammalian body. T o these advantages is added the immense array of
experimental interventions made possible by in vitro cultivation.
T o understand cell division is a challenge of such magnitude that all
possible materials have been analysed with this aim in view. Almost
every year, symposia or general reviews are devoted to some special
aspect of cell division (e.g., in recent years, Anderson, 1956; Stern, 1956;
Mazia, 1956; Swann, 1957, 1958; Gross, 1960; Levine, 1961). These