ISLETS OF LANGERHANS 



167 



JALOWY 



as a sulfonated naphthyl-rosanilin or 

 naphthyl-pararosanilin. He questions 

 the synonym (alkali blue XG) given in 

 the Colour Index. This acid has been 

 much used as a Vital Stain in European 

 laboratories. It is not made in the 

 United States. 

 Islets of Langerhans of the pancreas . There 

 are many techniques for the study of 

 these cellular masses. 



1. To study in the living state the 

 method employed by O'Leary, J. L., 

 Anat. Rec, 1930, 45, 27-58 is recom- 

 mended. It consists essentially of 

 partly withdrawing the pancreas from 

 a mouse and of mounting it in such a 

 way that a thin film of tissue can be 

 closely examined with circulation still 

 active. The islet cells can be studied 

 with oil immersion lenses and the 

 changes in them on the injection of 

 insulin noted. 



2. To obtain an idea of the distribu- 

 tion, number and size of the islets 

 supravital staining with Neutral Red 

 or Janus Green is indicated, which see. 



3. To stain the cell types specifically 

 Neutral Gentian and other stains 

 advised by Lane, Bensley and their 

 followers are available. The Azan Stain 

 suggested by Bloom, W., Anat. Rec, 

 1931, 49, 363-371 (see his beautifully 

 colored plate), has been further investi- 

 gated by Gomori, G., Anat. Rec, 1939, 

 74, 439-459 whose technique abbreviated 

 is as follows : Fix thin slices of pancreas 

 in Bouin's fluid 8-10 hrs. Wash in aq. 

 dest. Imbed in paraffin and cut ifi sec- 

 tions. Stain 45-60 min. at 56°C. in 

 azocarmine. (To make dissolve 0.1% 

 azocarmine in aq. dest. Boil about 5 

 min. Cool and add 1.0 cc glacial acetic 

 acid to each 50 cc. solution. Before use 

 filter at 60 °C. Stain will keep for 

 months.) Rinse quickly inaq. dest. and 

 blot. Destain in 90% alcohol containing 

 1% aniline oil until acinous tissue is al- 

 most wholly decolorized and B cells 

 show red against pink background of A 

 cells. Rinse briefly and treat with 5% 

 aq. iron alum for 5 min. or more. Rinse 

 again and stain 2-20 min. in the usual 

 mixture (anilin blue, 0.5 gm.; orange 

 G, 2.0 gm.; + aq. dest. to make 100 cc.) 

 diluted with 2-3 times its volume of aq. 

 dest. until under the microscope colla- 

 genic tissue becomes deep blue. Rinse 

 and blot. Differentiate and dehydrate 

 in absolute alcohol, clear in xylol and 

 mount in balsam. Cytoplasm of A cells 

 rich orange yellow, of B cells fiery red 

 and of D cells sky blue. The author 

 states that by first staining with Bens- 

 ley's neutral gentian, decolorizing and 

 restaining by above Azan method it can 



be seen that there is no gradation be- 

 tween A and B cells. 



Isoelectric Points of cellular structures. 

 Methods for their determination at con- 

 trolled pll's by intensity of staining 

 have been critically evaluated by Levine, 

 N. D., Stain Techn., 1940, 15, 91-112. 

 His conclusion is that no true isoelectric 

 points have yet been established for 

 nucleus, cytoplasm or other tissue ele- 

 ments by tliese techniques. See re- 

 ticulo-endothelial cells (Fautrez, J., 

 Bull. d'Hist. Appl., 1936, 13, 202-200). 



Isohematein, as a biological stain (Cole, 

 E. C, Stain Techn., 1931, 6, 93-96). 

 Greater tinctorial power than hematox- 

 ylin but less selective. 



Isomerase with Aldolase are known as 

 Zymohexase. 



Isopentane recommended by Hoerr, N. L., 

 Anat. Rec, 1936, 65, 293 for freezing in 

 the Altmann-Gersh technique. 



Isopropanal in combination as a new fixative 

 for animal tissues which also dehydrates 

 (Cleverdon, M. A., Science, 1943, 97, 

 168). Isopropanal, 55 cc; picric acid, 

 5 gms., acetone, 30 cc; glacial acetic 

 acid, 55 cc; formalin (40% formalde- 

 hyde CP), 5 cc Fix 2 hrs.— 4 days de- 

 pending on size. Store in 70% iso- 

 propanal or imbed in paraffin after first 

 washing in 2 changes nearly absolute 

 isopropanal. Remove picric acid from 

 mounted sections just before staining 

 with 1.5% ammonium hydroxide in 95% 

 alcohol. 



Isopropyl Alcohol. Has been recommended 

 as a substitute for ethyl alcohol since it 

 mixes with water and xylol. It is said 

 to be less hardening than ethyl alcohol 

 (Bradbury, O. C, Science, 1931,74,225) 

 but it is more expensive. See Herman, 

 C. M., J. Lab. & Clin. Med., 1941,26, 

 1788. 



Isorubin, see New Fuchsin, 



Iso-Safrol is obviously an isomer of safrol 

 which is given as 3,4-methylene-dioxy- 

 allylbenzene in the Merck Index. Iso- 

 saf role is listed among Eastman's organic 

 chemicals. It is sometimes recom- 

 mended as a partly dehydrating and 

 clearing agent (Silver Citrate injection 

 of blood vessels, etc) but in all likeli- 

 hood other clearing agents can be used 

 as substitutes. 



Isospora, see Coccidia. 



Jacobson's Organ, innervation, Bellairs, 

 A., J. Anat., 1942, 76, 167-177. 



Jalowy modification of Hortega method for 

 the skin (Jalowy, B., Zeit. f. Zellf. u. 

 Mikr. Anat., 1937, 27, 667-690). To 

 make reagent wash ppt., formed by 

 adding 20 drops 40% aq. NaOH to 20 cc. 

 10% aq. silver nitrate, 10 times with 

 aq. dest. Suspend ppt. in 20 cc. aq. dest. 

 Add ammonia drop by drop till it dis- 



