11 



Survey of Cytological 



Techniques 



Outstanding progress has been made over the last decade in the de- 

 sign and use of instruments for the study of the organization and kinetics 

 of the cell. Future developments in this area would seem to be limited 

 only by the ingenuity of the cytologist in developing new experimental 

 tools or adopting instruments already in use in other fields such as 

 physics and chemistry. Much of the apparatus associated with physical 

 measurements of various kinds and biochemical analyses has been or is 

 in the process of being adopted for studies at the cellular level. In the 

 present chapter those methods which (1) are most widely used, and 

 (2) have given reliable results, will be outlined. The list is by no means 

 exhaustive nor are the descriptions of many of the techniques meant to 

 replace those found in the many excellent reviews available. 



FIXATION 



Cytological fixation is the treatment of living cells, usually with chem- 

 ical agents, to preserve their structural and or chemical components for 

 subsequent study. The very heterogeneity of living systems generally 

 makes it impossible to devise a fixation system which achieves all-round 

 perfection. At best, one attempts to find fixing agents or combinations of 

 agents capable of preserving certain predetermined features in a rea- 

 sonably "life-like" state. One very important requirement for any fixation 

 is that whatever alteration it does produce in the cell should be perma- 

 nent and consistent. 



209 



