ENAMEL 



88 



ENZYMES 



1918, 5, 529-531). Marshall (J. S., J. 

 Dent. Res., 1921, 3, 241-255) employed 

 Naphthamine brilliant blue similarly 

 as a vital stain. See Dentin, vital 

 staining. 



Endamoeba, see Entameba. 



Endolymph. To demonstrate its circulation 

 employ method used by Guild, S. R., 

 Am. J. Anat., 1927, 39, 57-81. Introduce 

 solution of potassium ferrocyanide and 

 iron ammonium citrate into cochlear 

 ducts of living guinea pigs under anes- 

 thesia. Kill at intervals up to 48 hrs. 

 Excise tissue and fix in acid fluid which 

 precipitates Prussian Blue wherever 

 the solution has circulated. 



Endospore stain for bacteria in blood smears. 

 Smear, air dry and fix by flaming 3 times. 

 5% aq. malachite green 5 min., wash in 

 tap water 10-20 sec. 0.5% aq. safranin, 

 10 sec, wash quickly, dry and examine 

 (Bruner, D. W. and Edwards, P. R., 

 J. Lab. & Clin. Med., 1939, 25, 543-544). 



Enrichment techniques, see Conceiitration. 



Entameba. Craig (p. 35) gives a useful 

 table of diagnostic features of intestinal 

 amebae in man; also, on p. 55, a list of 

 objects that maj'' be mistaken for 

 amebae in unstained and stained prepa- 

 rations; and details as to media for cul- 

 tivation of which the Boeck and Doboh- 

 lav media and the simpler Craig media 

 are the most helpful. 



This genus includes E. histolytica, 

 the cause of amebic dysentery and E. 

 coli and E. gingivalis , two apparently 

 harmless commensals. The technique 

 is essentially the same for all three. 

 In searching for E. histolytica or E. coli 

 take a small amount of fresh feces, mix 

 with physiological saline solution and 

 examine directly. Recognize amebae 

 by large size and movements if slide 

 •iskeptwarm. E. histolytica frequently 

 contains erythrocytes. Mallory (p. 

 296) advises mixture with Gram's 

 Iodine solution to demonstrate glycogen 

 if present, or mixing with drop 1-2% 

 formalin, then treatment with drop 2% 

 acetic acid and coloration with 1 drop 

 1% aq. neutral red. E. gingivalis is to 

 be found in decayed teeth. Only E. 

 histolytica extensively invades tissues. 

 1. To make permanent smear prepara- 

 tions (Mallorj', p. 296) fix thin smear 

 while moist in 95% alcohol, 1 part, and 

 sat. aq. corrosive sublimate, 2 parts, 

 for 15 min. Wash for few sec. in water 

 and cover with 1% alcoholic iodine for 

 3 min. Wash in aq. dest. imtil iodine 

 color is extracted. Wash again and stain 

 with Phosphotungstic Acid Hema- 

 toxylin, 30 min. Wash in water, dehy- 

 drate in 95 and abs. alcohol, clear in xylol 

 and mount in balsam. Nuclei and ecto- 

 sarc, deep blue; cytoplasm, bluish. 



2. To stain differentially in sections 

 (Mallory, p. 297). Fix in 95% or abs. 

 ale, and make paraffin or celloidin sec- 

 tions. Stain in 0.25% aq. thionin 3-5 

 min. Differentiate in 2% aq. oxalic 

 acid, |-1 min. After washing in water, 

 dehydrate in 95% and abs. ale. Clear 

 in xylol and mount in balsam, except for 

 celloidin sections which require clearing 

 in terpineol, or origanum oil, after 95% 

 ale. Nuclei of amebae brownish red, 

 those of all other cells, blue. See 

 lodine-Eosin stain and Walker's 

 Method. 



Enterochromaffin Cells. Perhaps the best 

 technique is Bodian's protargol method 

 as described by Dawson, A. B. and 

 Barnett, Julia, Stain Techn., 1944, 19, 

 115-118. For the influence of pilo- 

 carpin on enterochromaffin cells see 

 Hamperl, H., Ztschr. f. Mikr. Anat. 

 Forsch., 1925, 2, 506-535. See Small 

 Intestine. 



Entomological Techniques, see Mosquito, 

 Ticks, Insects, Arachnids, Parasites. 



Enzymes. Their name is legion. At pres- 

 ent only a few can be localized histo- 

 chemically within or near their cells of 

 origin. There is no better example of 

 advantageous association between histo- 

 logical and biochemical methods. At 

 present four principal kinds of technique 

 are employed for localization: (1) By 

 spectrographic identification in the 

 tissues — especially the Cytochrome 

 Oxidases, (2) By close comparison of 

 enzymatic properties with cellular com- 

 position of the tissues — Amylase, Pep- 

 sin, Peptidase, Esterase, Protease, 

 Cholinesterase, Lipase, Urease, Car- 

 bonic Anhydrase, etc., (3) By separation 

 of nuclei from cytoplasms by differential 

 centrifugation and by estimation of 

 enzyme in each — -Arginase, and in sepa- 

 rated cytoplasmic granules Adenylpyro- 

 phosphatase. (4) By the development 

 of characteristic products within the 

 cells or tissues — Cytochrome Oxidase, 

 Oxidase, Phenolase, Peroxidase, Phos- 

 phatase, Dopa Oxidase. See also Nu- 

 clease, Cathepsin, Lysozyme and 

 Adenosinase. The terms lyo- and 

 desmoenzymes are used to indicate re- 

 spectively the enzymes which can and 

 cannot be separated from cell proteins. 

 Whether dyes are of any service as 

 indicators of the presence of enzymes 

 remains to be determined. However 

 Robertson, T. B., J. Biol. Chem., 1906, 

 2, 317-383, found that a little safranin 

 added to a solution of trypsin forms a 

 colored ppt. and Holzberg, H. L., J. 

 Biol. Chem., 1913, 14, 335-339 observed 

 that the ppt. exhibits proteolytic ac- 

 tivity, and Marston, H. R., Biochem. 

 J., 1923, 17, 851-859, discovered that 



