SUDAN BLACK Bj 



328 



SULFHYDRYL GROUPS 



sium bichromate 6 cc; 2% chromic 

 acid, 3 cc. ; and aq. dest. 5 cc. Wash in 

 running water 24 hrs. In case tissue 

 is delicate and requires support embed 

 in gelatin before cutting frozen sections : 

 12.5% gelatin in 1% aq. phenol filtered, 

 37°C., 24 hrs. 25% solution, same. 

 Embed in fresh 25% aq. gelatin, cool, 

 trim, harden in 6% formalin 24 hrs. 

 Cut frozen sections, whether first em- 

 bedded in gelatin or not, 5-10 microns 

 thick. Transfer to aq. dest. and then 

 into 50% diacetin agitated 30 sec. To 

 make stain, add excess Sudan Black B 

 (I.G.F.) to equal volumes of diacetin 

 and aq. dest., incubate at 55°C. for 2 

 days. Cool. Before use filter off 

 amount required. Stain 15 micron sec- 

 tions 2 hrs. If speed is necessary warm 

 in paraffin oven. 50% diacetin 30 sec. 

 Counterstain with carmalum. Place 

 in dish of water with care making sec- 

 tions "spin on surface and flatten." 

 Float on to slide and mount in Apathy's 

 medium. Nuclei red, lipids including 

 myelin black (Leach, E. H., J. Path. & 

 Bact., 1938, 47, 635-637). Diacetin is 

 glycerol diacetate introduced as solvent 

 for scharlach R by Gross (W., Zeit., 

 wiss. Mikr., 1930, 47, 64). Since Leach 

 does not specify what Apathy's medium 

 is, it is suggested that temporary 

 mounts be made in glycerin. 



2. For myelin (Lison, L. and Dag- 

 nelie, J., Bull. d'Histol. Appl., 1935, 

 12, 85-91). To stain lipoid granules in 

 leucocytes. Dry blood smear and fix 

 in methyl alcohol, 30 sec. Stain in a jar 

 with sat. Sudan black B in 70% alcohol, 

 30min. Rinse in water and wash 1 min. 

 in 70% alcohol to remove deposit. 

 Counterstain with sat. alcoholic eosin in 

 70% alcohol, 30 sec. Wash and stain 

 in sat. aq. methylene blue 3 min. Rinse, 

 blot dry and examine with oil immersion. 

 Lipoid granules, deep black; nuclei, 

 blue; and erythrocytes, red. (Sheehan, 

 H.L ,J. Path. & Bact., 1939, 49, 580-581). 



Sudan Black Bi as a bacterial fat stain. 

 Sat. sol. of Sudan black B (Nat. Aniline 

 and Chemical Co.) in 70% alcohol, or 

 in ethylene glycol stains fat bodies in 

 bacteria deep blue black (Hartman, T. 

 L., Stain Techn., 1940, 15, 23-28). 



Sudan Blue G, Brown 5 B, Corinth B, as fat 

 stains (Lillie, R. D., J. Lab. & Clin. 

 Methods, 1944, 24, 35-42). This gives 

 good account of all oil soluble dyes as 

 fat stains. 



Sudan Dyes suspended in watery media 

 for use in the staining of fat are de- 

 scribed by Telford Govan, A. D., J. 

 Path. & Bact., 1944, 56, 262-264. While 

 stirring add sat. Sudan dye in acetone 

 drop by drop from capillary pipette to 

 1% aq. gelatin containing 1% acetic 



acid to development of a deep brick-red 

 color and a milk like consistency. 

 Evaporate acetone for 2 hrs. at 37°. 

 Remove sediment by filtration. Cut 

 frozen sections. Transfer them from 

 water to 1% aq. gelatin for 2-3 min. 

 Stain for 30 min. at 37° in above de- 

 scribed dye suspension. Wash in 1% 

 aq. gelatin 2-3 min. and thoroughly in 

 water. Mount in glycerin jelly, see 

 Glycerine Jelly or in Karo Syrup. 



Sudan G, see Sudan III. 



Sudan Hydrotropes. Sudan stains are rela- 

 tively insoluble in water. They can be 

 changed to hydrotropes (Neuberg) which 

 are water soluble. The hydrotropes of 

 red lipid stains are of a blue color 

 which changes to red when the dye 

 passes into a lipid or a lipid solvent. 

 This is the basis of a useful technique 

 for lipids (Hadjioloff, A., Bull. d'Hist. 

 Appl., 1938, 15, 37-41). 



Sudan R (CI, 113)— brilliant fat scarlet B, 

 oil Vermillion — A weakly acid mono-azo 

 dye. 



Sudan Red, see Magdala Red. 



Sugars, see Reducing Sugars. 



Sulfatase. An enzyme capable of hydrolyz- 

 ing sulfuric acid from its ester linkages. 

 Since cartilage, mucus and many de- 

 toxification products contain esterified 

 sulfuric acid, an understanding of the 

 localization of this enzyme would be 

 most interesting. Seligman, A. M., 

 M. M. Nachlas, L. H. Maunheimer, O. 

 H. Friedman and G. Wolf, Ann. Surg., 

 1949, 130, 333-341, describe a method 

 involving the hydrolysis of beta naph- 

 thyl sulfate and subsequent diazotiza- 

 tion of the enzymatically liberated 

 naphthol. 



Sulfhydryl Groups. 1. Prussian blue histo- 

 chemical reaction for (Chevremont, M. 

 and Frederic, J. Arch, de Biol., 1943, 

 54, 589-605). Fresh or fixed tissue sec- 

 tions or smears can be used. Formol, 

 formol Ringer (saline) and Bouin are 

 suitable fixatives; but fluids containing 

 sublimate, such as those of Zenker and 

 Helly are contraindicated. The opti- 

 mum time of fixation is from a few hours 

 to one day. Time of heating during 

 paraffin embedding should be reduced 

 to a minimum. Wash sections care- 

 fully in aq. dest. to remove formalin. 

 Plunge sections or smears in 3 succes- 

 sive baths of the following mixture: 

 1 part fresh 0.1% aq. ferricyanide of 

 potassium (For Analysis, C.P.) and 3 

 parts 1% aq. ferric sulphate (For Anal- 

 ysis, C.P.). The mi.xture thus pre- 

 pared has a pH of 2.4 and, in ordinary 

 light, it is stable for 2 hrs.; in darkness 

 it lasts longer. The time in the baths 

 is approximately 10-20 min. for frozen 

 sections, 20-25 min. for paraffin sections 



