WEIGERT METHOD 



266 



WEIL'S METHOD 



O'Leary's Brazilin method. All large 

 blocks of brain or spinal cord should be 

 imbedded in celloidin, the length of time 

 in celloidin and the type of celloidin to 

 be used being determined by the thick- 

 ness of the sections desired. The fol- 

 lowing general rules apply to the block 

 mordanting of material to be stained by 

 the Weigert method : 



1. If it is advisable to stain nerve cells 

 and myelinated fibers in alternate sec- 

 tions, it is best to forego block mordant- 

 ing in Miiller's fluid. Formalin fixed 

 blocks are imbedded directlj^ in celloidin 

 and alternate sections are stained by 

 Weil's Method and the Gallocyanin 

 Technique. 



2. If only staining by a Weigert pro- 

 cedure is contemplated, the blocks may 

 be mordanted in Miiller's fluid for sev- 

 eral weeks to several months depending 

 upon the size of the block, imbedded in 

 celloidin and stained by the Weigert-Pal 

 method. 



3. In special cases (cerebral cortex) 

 the small myelinated fibers are stained 

 completely with great difficulty. Blocks, 

 premordanted or not, are sectioned in 

 celloidin and the sections given long 

 mordanting (one week to one month) in 

 Miiller's fluid. Stain by Kultschitzky 

 modification of Weigert or Weigert-Pal. 



Weigert's Mordants. (1 ) Primary, or rapid 

 mordant: potassium bichromate, 5 gm.; 

 Fluorchrome, 2 gm.; boiling aq. dest., 

 100 cc. (2) Secondary, or copper, or 

 neuroglia mordant: boil 2.5 gm. Fluor- 

 chrome with 100 cc. aq. dest. Take 

 away flame. When boiling has stopped, 

 add 5 cc. glacial acetic acid, then 5 gm. 

 finely powdered copper acetate. Stir 

 vigorously until dissolved and cool. 



Weigert Pal Method. For myelin sheaths 

 (Dr. J. L. O'Leary, personal communi- 

 cation). Fix in 10% formalin, 1-2 wks. 

 Wash in running tap water, 3 hrs. Mor- 

 dant in Miiller's fluid 1 wk. to 3 mo. 

 depending on the size of block. Change 

 Miiller's thrice weekly at first, later once 

 weekly. Wash in running tap water, 6- 

 12 hrs. Imbed in celloidin. Cut sec- 

 tions 20-100 M depending upon size of 

 block and detail desired. 0.25% aq. 

 chromic acid, 3-5 hrs. 3 changes aq. 

 dest. 10% hematoxylin in abs. ale. 

 ripened and diluted to 1% with aq. dest. 

 prior to use, 12-24 hrs. 3 changes of aq. 

 dest. Differentiate in Pal's fluid (ox- 

 alic acid, 1 gm.; potassium sulphite, 1 

 gm. ; aq. dest., 200 cc), alternating with 

 0.25% aq. potassium permanganate if 

 differentiation is too slow. Wash in 3 

 changes aq. dest. Dehydrate in 2 

 changes 95% ale. Clear in carbol- 

 creosol-xylol followed by pure toluol. 

 Mount in balsam. Myelin sheaths, deep 



black; background, unstained. Ano- 

 ther variation of the Pal-Weigert method 

 is given by Clark, S. L. and Ward, J. W., 

 Stain Tech., 1935, 10, 53-55. See John- 

 son's Neutral red for counterstain. 

 Weigert's Borax Ferricyanide. Borax, 1 

 gm.; potassium ferricyanide, 1.25 gm.; 

 aq. dest., 100 cc. A fluid for differentia- 

 tion of hematoxylin stain in Weigert's 

 method. Employed also in copper 

 chrome hematoxylin method of Bensley. 

 Weigert's Resorcin-Fuchsin. Stain for elas- 

 tic fibers. Given by Mallory, p. 168. 

 Add 2 gm. basic fuchsin and 4 gm. resor- 

 cin to 200 cc. aq. dest. Boil in enamel 

 dish and while boiling, add 25 cc. 29% aq. 

 ferric chloride. Stir and boil 2-5 min. 

 Cool. Collect ppt. and discard filtrate. 

 Dry ppt. on filter paper and return both 

 to the enamel dish which has also been 

 dried. Add 200 cc. 95% alcohol, warm 

 carefully, stir and discard filter paper 

 when ppt. is dissolved out. Cool, add 

 95% alcohol to 200 cc. and 4 cc. hydro- 

 chloric acid. Mixture keeps well. For- 

 malin fixed material is preferred, but 

 most other fixatives are satisfactory. 

 Stain paraffin sections, after removing 

 paraffin, for 20 min. or more in above mix- 

 ture. Wash off excess in 95% alcohol and 

 differentiate in Acid Alcohol if required. 

 Wash thoroughly in tap water. Dehy- 

 drate, clear and mount. Elastic fibers 

 dark blue black. It is well to stain nu- 

 clei with Lithium Carmine (Orth's) 

 before coloring the elastic tissue. Wei- 

 gert's resorcin fuchsin for elastic tissue 

 has been supplemented by Masson's 

 trichrome for other connective tissue 

 components in a helpful way by Mende- 

 loff, J. and Blechman, H.. Am. J. Clin. 

 Path., Techn. Suppl., 1943, 7, 65. 

 Weight measurements 



1 kilogram = 2.2 lbs., or 35| ounces 



1 gram = 155 grains 



1 pound = 453.6 gms. 



1 ounce = 28.4 gms. 



1 drachm = 3.89 gms. 



1 grain = 0.065 gms. 



The Troy pounds and ounces are dif- 

 ferent but seldom used. For weights 

 of organs, see Normals. 

 Weil's Method. For myelin sheaths (Weil, 

 A., Arch. Neurol, a. Psychiat. 1928, 20, 

 392 and Weil, A., Textbook of Neuro- 

 pathology, 2nd. ed. p. 328. New York 

 1945. Place celloidin sections of for- 

 malin fixed material (not yet mor- 

 danted) in aq. dest. Stain for 15 min. 

 at 45-50°C. in equal parts of 4% aq. 

 iron alum and 1% aq. hematoxylin pre- 

 pared from 10% sol. in abs. ale. at least 

 6 months old. (Note: do not filter this 

 stain; do not use it twice; mix fluids 

 just before using.) Wash 2 times in 

 tap water. Differentiate in 4% aq. 



