ULTRAVIOLET 



256 



UREASE 



(R. W. G. and A. L., J. Exper. Med., 

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

 teins absorb ultraviolet more strongly 

 than others, details can be brought out 

 with it not revealed by visible light. 

 This they demonstrate by experiments 

 with 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. 



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 cc; 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; collagenic 

 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-Andre'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 

 ^-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. 

 Employed by HoUande for bacteriocytes 

 of Periplaneta orientalis L (Hollande, 

 A. C., Bull. d'Histol. AppL, 1931, 8, 

 176-178). 



Urea. IVIany histochemical techniques have 

 been proposed. Leschke (E., Zeit. 

 Klin. Med., 1915, 81, 14-35) fixes in 

 half sat. sol. mercuric nitrate in 1% 

 nitric acid for 1 day, then washes in 

 frequently changed aq. dest., imbeds 

 in paraffin and treats the sections with 

 sat. aq. hydrogen sulphide staining 

 nuclei with hemalum. Stiibel (H., 

 Anat. Anz., 1921, 54, 237-239) fixes small 

 pieces in 6% xanthydrol in glacial acetic 

 acid 6-12 hrs., imbeds in paraffin, stains 

 sections by ordinary methods and 

 examines by polarizing microscope. 

 Oliver (J., J. Exper. Med., 1921, 33, 

 177-186) employs instead a solution 

 containing 2 gm. xanthydrol, 10 cc. 

 methjd alcohol and 20 cc glacial acetic 

 acid. Lison (p. 169) criticizes these 

 methods severely. 



Urease. A method for determining the 

 distribution of urease in the gastric 

 mucous membrane (pylorus and fundus) 

 of the dog has been described and used 

 by Linderstr0m-Lang and Ohlsen (K. 

 and A. S., Enzymologia, 1936-37, 1, 

 92-95). Cylinders of tissue (2.5 mm. 

 in diameter) are cut vertical to the 

 surface from frozen mucosa. Cross 

 frozen sections (25 microns thick) 

 of the cylinders are then tested for 

 urease. This is concentrated in the 

 surface layers containing cells stainable 

 with mucicarmine. Chief cells in the 

 bases of the glands are inactive in both 

 fundus and pylorus and the authors 



