Fluorescence Microscopy 

 The fluorescence microscope takes advantage of the fact that certain 

 substances emit visible light when illuminated with ultraviolet, violet, 

 or blue radiation. This property is spoken of as autofluorescence, and 



\FLUORESCENCE 



300 340 380 420 460 500 

 WAVE LENGTH, m X 



540 580 



Figure 11-27. Graph Showing Absorption and Fluorescence Spectra of 

 Sodium Fluorescein. (From Mellors, R. C. 1959. "Fluorescent-Antibody 

 Method," in Mellors, R. C. (Ed.), "Analytical Cytology," 2nd ed.. McGraw- 

 Hill Book Co., Inc., New York, N. Y., Fig. 1.8, p. 24. After Ghosh, I. C. 

 and Ssngupta, S. B., 1938. "Studien liber Fluorescenzvermogen, Absorptions- 

 spektra und elektrische Leitfahigkeiten an Fluorescein, Rhodamin und 

 Acriflavin in wasserigen Losungen," Zeits. Physik. Cheinie, ABT - B, 41, 

 Fig. 3, p. 128.) 



is exhibited by such substances as chlorophyll, porphyrin, riboflavin, and 

 vitamin A. Nonfluorescent substances (e.g., proteins, carbohydrates) 

 can be made to show secondary fluorescence by combining them with 

 fluorescent dyes called fluorochromes. Examples of fluorochromes and 

 the color of light they emit on exposure to shorter wavelength radiation 



SURVEY OF CYTOLOGICAL TECHNIQUES / 249 



