ULTRAVIOLET MICROSPECTRO- 

 PHOTOMETRY 



365 



URATES AND URIC ACID 



Ultraviolet Microspectrophotometry has 



been developed by T. Caspersson (Cell 

 Growth and Cell Function. A Cyto- 

 chemical Study. W. W. Norton and 

 Company, New York, 1950) and per- 

 mits the determination of absorption 

 curves of light from 240 to 350 milli- 

 microns w^avelength in minute parts 

 of cells. Information on steroids, nu- 

 cleic acids, proteins and iodides can 

 be obtained. Equipment is being de- 

 veloped now in several laboratories 

 to extend the range of measurements 

 from 230 niM to the infra red and the 

 usefulness of these types of technics. 



Ultraviolet Photomicrography has certain 

 advantages over visible light photo- 

 micrography because the resolving 

 power of the former is greater in conse- 

 quence of its shorter wave length, and 

 as pointed out by Wyckoff and Louw 

 (R. \V. G. and A. L., J. Exper. Med., 

 1931, 54, 449-451), because some pro- 

 teins absorb ultraviolet more strongly 

 tlian others, details can be brought out 

 with it not revealed by visible light. 

 This they demonstrate by experiments 

 w^ith B. subtilis. It was then found 

 that the substances that strongly ab- 

 sorb ultraviolet light give a positive 

 Feulgen reaction (Wyckoff, R. W. G., 

 Ebeling, H. H., and Ter Louw, A. L., 

 J. Morph., 1932, 53, 189-199) and that 

 they also yield conspicuous mineral 

 ash on microincineration (Scott, G. H., 

 Science, 1932, 76, 148-150)— an inter- 

 esting superposition of three technical 

 methods. The work of the Swedish 

 group is summarized in Caspersson's 

 book (Cell Growth and Cell Function. 

 A Cytochemical Study, W. W. Norton 

 and Co., New York, 1950). Two avail- 

 able articles in the American literature 

 are by Stowell (Arch. Path. 1948, 46, 

 164-178 and Cancer, 1949, 2, 121-131). 

 The use of other newer types of lenses 

 should be mentioned. See (Mellors, 

 R. C, Berger, R. E., and Streim, H. 

 G., Science, 1950, 111, 627-632 for refer- 

 ences). 



Union Green B, see Janus Green B. Ultro- 

 pak illuminator of Leitz is helpful for 

 micrological work. The Epi Condenser 

 W of Zeiss is similar. See Chambers, 

 R. W. and Kopac, M. J. in McClung's 

 Microscopical Technique, 1950, p. 508. 



Unna's Orcein method for elastic fibers. 

 This is simple and direct. Stain paraf- 

 fin sections, after almost any fixation, 

 in: orcein, 1 gm.; absolute alcohol, 

 100 CO. ; and hydrochloric acid, 1 cc. for 

 several hours. Wash in 70% alcohol 

 and sharpen the deep brown coloration 

 of the elastic fibers by removing excess 

 stain from background by destaining 



under the microscope in 95% alcohol 

 plus a trace of hydrochloric acid. 

 Wash in 95%, dehydrate, clear and 

 mount. If desired counterstain with 

 methylene blue. 



Dahlgren (McClung, p. 425) advises 

 a modification of this stain for Muscle. 

 After sublimate fixation stain sections 

 24 hrs. in Wasserblau, 0.25 gm.; abso- 

 lute alcohol, 60 cc; orcein, 1 gm.; 

 glycerin, 10 cc; water, 30 cc. Wash 

 in 70% alcohol, dehydrate, clear and 

 mount. Muscle, purple; coUagenic 

 fibers, blue; elastic fibers, red. It is 

 important in doubtful cases to compare 

 with similar tissue colored by other 

 specific stains before identification of 

 muscle is assured. 



Uranin, sodium salt of Fluorescein. 



Uranium. Salts injected into tissues can 

 be demonstrated by (1) a method of 

 Schneider (G., Skand. Arch. Physiol., 

 1903, 14, 383-389). Fix in : 5% aq. 

 potassium ferrocyanide, 50 cc, sat. aq. 

 picric acid, 50 cc. ; hydrochloric acid, 

 10 cc. Wash in 4% aq. hydrochloric 

 acid and then in 80% alcohol acidified 

 with hydrochloric acid. Imbed and 

 cut. The uranium ferrocyanide of 

 potassium is detected by its dark brown 

 color (Lison, p. 103). (2) the Prussian 

 blue reaction for iron as employed by 

 Gerard and Cordier (P. and R., Arch. 

 Biol., 1932, 43, 367-413). According to 

 Lison this method is highly specific. 

 The possibility of detecting uranium 

 salts in incinerated sections by their 

 fluorescent properties in ultraviolet 

 light has been described (Policard, A. 

 and Okkels, H., Abderhalden's Handb. 

 d. biol. Arbeitsmethoden, 1931, 5, 1815). 

 Gordon H. Scott has been successful 

 when large amounts are present but 

 has called attention to complicating 

 factors (McClung's Microscopical Tech- 

 nique, p. 660). 



Urates and Uric Acid. A modification of 

 Courmont-Andr^'s method is suggested. 

 Neutralize some formalin with calcium 

 carbonate. Fix tissue in equal parts 

 1% aq. silver nitrate and 4.4% neutral 

 formalin in darkness, 12-24 hrs. Wash 

 in several changes aq. dest., 24 hrs. 

 Imbed in paraffin. Stain sections 

 hematum 10 min.; running tap water 

 i-1 hr. ; 1% aq. orange G or eosin ^1 

 hr. Wash quickly in aq. dest. Place 

 in 0.5% aq. phosphomolybdic acid, rinse 

 in aq. dest. and color in 0.12% aq. light 

 green, 1-10 min. Differentiate quickly 

 in 96% alcohol, dehydrate in iso-amyl- 

 alcohol, clear in xylol and mount in 

 balsam. Urates, black; chromatin, 

 blue; protoplasmic inclusions red to 

 orange and collagenic fibers, green. 



