GARDNER 



138 



GELATIN E^IBEDDING 



Gardner, see Articular Nerve Terminals. 



Garven's Gold Chloride method for nerve 

 endings in muscle (Garven, H.S.D., 

 Brain, 1925, 48, 380-441). This is Fis- 

 cher's modification of Ranvier's tech- 

 nique as used in Golgi's Laboratory. 

 Immerse small pieces of tissue in 25% 

 aq. pure formic acid and tease a little 

 to assure penetration 10-15 min. Blot 

 with clean cloth. Place in 1% aq. gold 

 chloride just sufficient to completely 

 cover tissue and shake. Avoid all iron 

 instruments. Cover dish with blue or 

 yellow glass. Leave 20 min. Blot 

 with clean cloth and repeat above treat- 

 ment with formic acid and gold leaving 

 this time in latter 24 hrs. in absolute 

 darkness. Repeat still again. Pass to 

 glycerin and leave in closed vessel in 

 ordinary light. The sharpness of the 

 intensely purple black nerves in a 

 lightly colored background increases 

 with time. Small pieces can then be 

 transferred to aq. dest. and the indi- 

 vidual fibers separated. This is facili- 

 tated by dissociation in dilute nitric 

 acid. Wash and make final mounts in 

 glycerin. The author used panniculus 

 carnosus of hedgehog, striated muscle 

 of frog and lizard, extrinsic eye muscle 

 of rabbit and human pectoral muscle. 



Gas Analysis. — Techniques are given in de- 

 tail by Glick, pp. 313-412. 



Gash-Irrigation recovery method for lung 

 cells (GI).— Written by C. C. Macklin, 

 Dept. of Histological Research, The 

 University of Western Ontario, London, 

 Canada. November 28, 1951. — Fresh 

 collapsed mouse or other mammalian 

 lung is cut through a drop of physiologi- 

 cal salt solution, blood serum or other 

 suitable liquid, inverted and drained 

 onto a slide. It is then covered and ex- 

 amined as a fresh mount, or spread, 

 dried, stained and mounted like a blood 

 smear. Liberated phagocytic and gran- 

 ular pneumonocytes (dust and foam 

 cells — which see) are thus obtained 

 (Macklin, C. C, Proc. 6th Intern. Con- 

 gress of exper. Cytol., Stockholm, 1947; 

 published 1949, 383-387; Macklin, C. C, 

 The Lancet, Feb. 24, 1951, 432-435). 



Gastric Contents. Examine microscopically 

 material obtained by stomach tube after 

 test meal as described by Stitt (p. 753). 

 Look for mucus, epithelial cells, leu- 

 cocytes, Gram positive bacilli in 

 smears. 



Gastrointestinal Tract. Immediate fixation 

 is desirable because postmortem changes 

 occur especially quickly. Do not wash 

 first with water but with physiological 

 saline or with the fixative itself. It may 

 be desirable to place the excised pieces, 

 with peritoneal surface down, on wooden 

 tongue depressor or stiff paper. Some 



flattening is required. The mucous 

 surface must not be allowed to dry. 

 See Small and Large Intestine. See 

 Papanicolaou Techniques. 



Gautheria Oil used to be employed as a 

 clearing agent. It has been displaced 

 _ by the artificial oil, methyl salicylate. 



Geiger Counters are instruments for the 

 counting of electrons which provide 

 quantitative data of great importance 

 in this electron age. A concise descrip- 

 tion of the history of counter develop- 

 ment and of the Geiger-Miiller type is 

 supplied by Rovner, L. in Glasser's 

 Medical Physics, 487-495. 



Gelatin-Carmine injections, see Carmine 

 Gelatin injections. 



Gelatin Glue, method of mounting sections, 

 see Masson's. 



Gelatin Imbedding and Sectioning. This is 

 used when sections are required of loose, 

 friable tissues which easily fall apart. 

 Since the imbedding is directly from 

 water, no alcoholic or other dehydration 

 is required. Probably the best method 

 is that of Zwemer (R. L., Anat. Rec, 

 1933, 57, 41-44), devised primarily for 

 the study of adrenal lipoids. Wash 

 material fixed in formalin or other fluid 

 in water, 4 hrs. 5% gelatin in incubator 

 at 35-37 °C. 24 hrs. 10% gelatin at same 

 temperature, 12-16 hrs. Imbed by 

 placing in 10% gelatin in Petri dish in 

 refrigerator. Cut out blocks of tissue 

 and fix in 10% formalin several hours 

 to make gelatin insoluble in water. 

 In this formalin solution tissues can be 

 preserved indefinitely. Before section- 

 ing rinse block in water and trim. 

 Freeze with CO2 until block is uniformly 

 white. Allow to thaw until knife cuts 

 easily. Sections as thin as 5 microns 

 can be obtained. Float onto slide in 

 aq. dest. Drain off excess water and 

 run a drop or two of 1% gelatin under 

 setion. Again drain off excess. After 

 heating in drying oven at 33-37°C. place 

 slide in 10% formalin for 10 min. to fix 

 gelatin. In this formalin solution the 

 mounted sections can be stored. Stain 

 sections in usual way with Sudan, Nile 

 Blue Sulphate, Osmic Acid, Laidlaw's 

 Silver Method, and mount in Gly- 

 chrogel. 



Wright's method as described by 

 Mallory (p. 34) is much quicker and is 

 recommended for fragmented tissues 

 such as those from curettings. Make a 

 10% solution of gelatin in warm aq. 

 dest. and while still fluid add 0.5% 

 carbolic acid. Do not overheat. The 

 tissue, unfixed or fi.xed, preferably in 

 10% formalin, is "dried" and placed in 

 a small "pool" of gelatin liquified by 

 heat on a or slide in a glass vessel. This 

 is allowed to solidify in the ice box for 



