SECTION TWO 



latter may precede morphological changes, which themselves may 

 be a consequence of abnormal cytochemistry, the fluorescence 

 method may allow an earlier detection of abnormal changes. 



The Staining Technique 



Equipment : 



1. A high-pressure mercury vapour 200 watt burner (e.g. 

 HBO 200) in a lamp housing. 



2. Two blue filters, to be inserted between the light source 

 and the microscope mirror. 



3. One (or a combination of two) yellow filter(s) to be placed 

 in the ocular(s) to prevent ultra-violet light from reaching the 

 eyes. 



Note: The items listed above are essentially the same as those 

 specified by E. Gurr (195 1, 1956), for general fluorescence 

 microscopy. 



It might also be mentioned here that an expensive microscope 

 is not necessary. Good results are obtainable in fluorescence 

 microscopy even with a cheap or antiquated microscope so long 

 as it is fitted with objectives up to i /6-inch focal length and has 

 a suitable ocular. Moreover a completely darkened room is not 

 necessary (E. Gurr, i960). 



Photography : 



Photographs can be taken with a 35-mm. camera back, attached 

 to the microscope and using a fast colour film, such as Daylight 

 High Speed Ektochrome or Tungsten Super Anscochrome films. 

 Exposure times range from a few seconds to several minutes, 

 depending on magnification, fluorescence set-up, and length of 

 time that the mercury burner has been in use. 



Pre-screening : 



Smears are carefully scrutinized field by field to ascertain 

 whether or not they contain cells with orange or red fluorescence. 

 Most normal smears show only cells with greenish, brown, or 

 reddish brown fluorescence, and these samples should be dis- 

 carded. Cells exhibiting orange or red cytoplasm are to be found 



95 



