SECTION TWO 



and oral epithelia (present in sputum), exhibit brown or green 

 cytoplasm, depending whether they originate from the basal or 

 the superficial layers of the stratified epithelium. 



In contrast, malignant cells fluoresce conspicuously in bright 

 orange to red.* 



On account of their distinct and very conspicuous fluorescence, 

 malignant cells in sputum, bronchial secretions and pleural fluids 

 are readily recognizable even with magnifications as low as x loo. 



Mahgnant cells, whether they occur in the respiratory, digestive, 

 urinary or female genital tract, body fluid, or other material are 

 characterized by bright orange to flaming red fluorescence of the 

 cytoplasm, and often by greenish-yellow hyperchromatic nuclei. 



Readers should consult the original papers (F. D. Bertalanffy, 

 1960a, i96oZ>; L. von BertalanflFy & F. D. Bertalanffy, i960) for 

 further information and colour plates. 



Notes: 



{a) After screening, smears may be destained in 50% alcohol 

 and reprocessed for any conventional procedure. They may 

 then be returned to the fixative, which also removes the acridine 

 orange, to be restained later with that dye if desired; or they 

 may be dried and stored, 



{b) It is stated in the original paper that the acridine orange 

 fluorescence method has been tested in 25,000 cases in which 

 there was a high rate of malignancy of the genital tract. Speci- 

 mens consisted of screening material from asymptomatic women 

 in the general population, routine samples from the gynaecologist, 

 and exfoliated material of all kinds. 



{c) It should be noted that Trichomonas vaginalis organisms 

 have brownish-red cytoplasm and small, yellow nuclei. The 

 mycelia and spores of Monilia albicans fluoresce bright red, while 

 bacteria appear red to reddish brown. 



[d] As already stated, when acridine orange is applied to 

 exfoliated cells according to the procedure described above, DNA 

 of the nucleus fluoresces in green, while RNA of the cytoplasm 

 fluoresces in brown, reddish-brown, orange, or bright red, 

 depending upon whether relatively small or relatively large 



* But not all cells that fluoresce in these colours are necessarily malignant. 

 Bright orange or red fluorescent cytoplasm is indicative of a high content of 

 RNA, and this occurs in normal " active " cells (see page 96). 



99 



