STAINING, PRACTICAL AND THEORETICAL 



in some smears, and these should be regarded as suspicious and 

 put aside for further evaluation, as " fluorescence suspicious ". 

 Not all these smears will contain malignant, or even cytologically 

 suspicious cells. Cells found to fluoresce in orange or red may 

 prove to be the normal " active " type. Such cells, because of 

 their increased proliferation, contain more RNA and thus fluoresce 

 more intensely than " inactive " cells. During final evaluation, 

 smears showing such cells will be eliminated on the basis of their 

 normal morphology. Material from the female genital tract, body 

 fluids, and urine, is particularly suitable for pre-screening by 

 those who, while not having had extensive training and experience 

 in cytology, have undergone a short course of instruction and 

 have acquired also a reading knowledge of the subject. The pre- 

 screening procedure thus lends itself especially well for the 

 private medical practitioner, reducing the number of smears of 

 some material to be submitted to a cytologist or cytopathological 

 laboratory by 80% or 90%. 



It is stressed, however, that pre-screening of respiratory 

 material, oral smears, and gastro-intestinal material should be 

 undertaken only by those who have acquired some considerable 

 experience in pre-screening other material first. 



Screening for final diagnosis: 



This should be performed only by fully experienced cyto- 

 pathologists or cytologists, or others fully trained and experienced 

 in exfoliative cytology. The final evaluation should not be based 

 upon cytoplasmic fluorescence only, and should not be attempted 

 by individuals not fully competent in exfoliative cytology, as 

 previously stated. The trained cytologist, scanning smears with 

 low magnification (e.g. x 100) regards increased fluorescence of 

 some cells as a warning signal. The final diagnosis is established 

 by consideration of the morphological characteristics of these cells. 

 Increased fluorescence of suspicious and malignant cells, serving 

 as a warning signal, enables the cytologist to evaluate cytological 

 specimens more rapidly. Thus after using the acridine orange 

 fluorescence method, an increase of 100% in output has been 

 reported in some laboratories, according to F. D, Bertalanffy 

 (i960). 



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