FLUORESCENCE MICROSCOPY 



129 



FOOT'S METHODS 



sensitization with dyes and plant ex- 

 tracts. This extends considerably the 

 range of fluorescence microscopy and has 

 been developed chiefly by Haitinger 

 (loc. cit.) in conjunction with Hamperl 

 and Linsbauer. Various fluorescent al- 

 kaloids, azo dyes, primulins, auramine, 

 berberine sulfate, chelidonium, rhubarb 

 extracts, etc., are selectively absorbed 

 by certain parts of the cell and cause 

 them to show characteristic fluorescences 

 in ultraviolet light. Such substances 

 are called fluorochroraes. Sections of 

 tissue are immersed in such substances 

 for a short period of time before being 

 examined. Examples of the use of these 

 fluorochromes are found in papers by 

 Haitlinger (loc. cit.),. Jenkins (loc. cit.), 

 Clark and Perkins (W. M. and M.E., J. 

 Am. Chem. Soc, 1932, 54, 1228-1248), 

 Lewis (M. R., Arch. f. exp. Zellf., 1935, 

 17, 96-105) and Popper (H., J. Mt. 

 Sinai Hosp., 1940, 7, 119-132). A good 

 account of fluorescence microscopy of 

 insects is given by Metcalf, R. L.. and 

 Patton, R. L., Stain Techn., 1944, 19, 

 11-27. 



Noteworthy applications have been 

 made in the use of acridine derivative 

 dyes. Krebs and Gerlach (Am. J. 

 Roentgenol. Rad. Therap., 1951, 65, 

 93-98) have demonstrated that acridine 

 orange, C.I. 788, is a sensitive indicator 

 of the viability of cells following ther- 

 mal and radiational damage. The 

 same dye was used by Zeiger and Har- 

 ders (Z. Zellforsch., 1951, 36, 62-78) 

 for flurochroming of nerve tissues. In 

 a comprehensive investigation of 24 

 diaminoacridine stains by DeBruyn, 

 Robertson and Farr (Anat. Rec, 1950, 

 108, 279-307) it was found that nuclei 

 of many tissues and organs were vitally 

 fluorochromed without perceptible toxic 

 or degenerative effects. 



Primulin is recommended by 

 Schmidt-LaBaume and Jager (Arch. f. 

 Dermat. Syph., 1939, 179, 531) in an 

 ingenious method for visualizing sur- 

 face detail of the epidermis. 



A most interesting method of demon- 

 strating the distribution of the right 

 and left coronary arteries is given by 

 Peterson and Gibson (Med. Radiogr. 

 Photogr., 1951, 27, 14-17), who inject 

 the vessels with plastics containing 

 red and green fluorescing pigments. 

 The heart is then encased in a plastic 

 shell, following which the tissues are 

 digested by KOH. Finally, the shell 

 holding the arterial cast is filled with 

 the transparent plastic. Under ultra- 

 violet illumination the arterial system 

 is revealed with extraordinary clarity. 

 The use of fluorescein dyes in the diag- 

 nosis of malignancy with special refer- 



ence to tumors of the central nervous 

 system is described by Hubbard, T. B. 

 and Moore, C. E., J. Nat. Cancer 

 Inst., 1949, 10, 303-314 (good bibliog- 

 raphy). The Diaminoacridines are im- 

 portant vital stains for nuclei in the 

 sense that they accumulate within 

 nuclei without toxic action and can 

 there be revealed b}' fluorescence 

 microscopy (de Bruyn,P. P. H., Robert- 

 son, R. C. and Farr, R. S., Anat. Rec, 

 1950, 108, 279-307). See Vitamin A, 

 Tubercle Bacillus, Cell Injury, Ura- 

 nium, Porphyrins, etc. 



Fluorescence Spectra. The technique in 

 some detail is described for 3:4-Benz- 

 pyrene by Hieger, I., Am. J. Cancer, 

 1937, 29, 705-714 who thinks that the 

 photographs of the spectra can well be 

 studied by simple visual examination. 



Fluorescent Blue, see Resorcin Blue. 



Fluorescent X. A special type of reduced 

 neutral red (Clark, W. M. and Perkins, 

 M. E., J. Am. Chem. Soc, 1932, 54, 

 1228-1248) employed for tissue cultures 

 (Lewis, M. R., Arch. f. exp. Zelf., 

 1935, 17, 96-105). 



Fluorine, see Atomic Weights. 



Fluorochromes. See Fluorescence micros- 

 copy. 



de Fonbrune pneumatic micromanipulator 

 can be obtained from Aloe Scientific, 

 5655 Kingsbury, St. Louis 12, Mo. 



Foods. The examination of foods to ascer- 

 tain their suitability for human con- 

 sumption involves not only organolep- 

 tic tests (use of unaided senses, sight, 

 smell, taste, etc.), but direct micro- 

 scopic examination and certain cul- 

 tural, experimental feeding, and other 

 tests. The techniques for adultera- 

 tions, bacteria, fungi, crystals, spores, 

 parasites and so on are usually the 

 routine ones. However, much time 

 will be saved by knowledge as to what 

 to look for in each case, how to look and 

 the best means of making the observa- 

 tions accurately quantitative (Schnei- 

 der, A., The Microbiology and Micro- 

 analysis of Foods. Philadelphia: P. 

 Blakiston's Son & Co., 1920, 262 pp.). 



Foot's Methods. 1. Rapid silver impreg- 

 nation of reticular fibers (Foot, W. C, 

 J. Tech. Meth., 1929, 12, 117-119). 

 Fix in 10% formalin (not necessarily 

 neutral), Zenker's, Bouin's or Helly's 

 fluids, 24 hrs. Make paraffin sections. 

 Remove mercury, if present, with iodine. 

 Treat with 0.25% potassium permanga- 

 nate, 5 min. and 5% oxalic acid, 10 min. 

 Wash in aq. dest. Impregnate 15 min. 

 in following silver solution at 50°C. : Add 

 40 cc 5%, aq. NajCOa to 10 cc 10% aq. 

 AgNOa. Let precipitate settle. De- 

 rant supernatant fluid. Make up to 

 50 cc. with aq. dest. Shake, repeat sett- 



