MOUNTING MEDIA 



159 



MUCUS 



For frozen sections and tissues to be 

 mounted from water and aqueous solu- 

 tions various glycerin mixtures are 

 popular : Lactophenol, Glychrogel, 

 Brandt's and Kaiser's glycerin jellies. 

 Having taken the easiest one to prepare, 

 for their merits are about equal, the 

 tissue is mounted and covered and it is 

 necessary to seal the edges. In the case 

 of temporary mounts a little paraffin 

 applied with a heated scalpel, or wire, 

 will suffice. Lee (p. 230) advocates 

 Peter Gray's sealing medium made up 

 by melting together 4 parts anhydrous 

 lanolin, 1 part Canada balsam (dry) and 

 S parts resin which becomes solid on 

 cooling. Apply to edges in the same 

 manner as the paraffin. Kronig's ce- 

 ment is employed in Bensley's labora- 

 tory. Duco cement is very worthwhile 

 because it is insoluble in xylol, alcohol 

 and other chemicals used to clean micro- 

 scopic preparations. Mallory (p. 99) 

 dilutes it with an equal volume of ace- 

 tone. See Karo. 



For sections and tissues which are first 

 dehydrated and cleared the investiga- 

 tor must choose the mounting medium 

 best adapted to his purpose from a con- 

 siderable number proposed of which the 

 following are given elsewhere in this 

 book : Balsam, Cedar Oil, Clarite, 

 Colophonium, Damar, Diaphane, Eupe- 

 ral, Nevillite, Sandarac, Terpineol 

 Balsam. 



The chief desiderata are a medium 

 which will harden fairly quickly, which 

 will not become acid and bring about the 

 fading of anilin dyes and which will not 

 crack or develop granules. Clarite is 

 competing for first place with balsam; 

 because, to make the balsam neutral and 

 keep it so, is a troublesome job. Direc- 

 tions for its preparation are given by the 

 Bensleys (p. 39). But the balsam ordi- 

 narily purchased is satisfactory for 

 hematoxylin and eosin and iron hema- 

 toxylin preparations except when the 

 latter are counterstained with an anilin 

 dye. The writer used to employ cedar 

 oil (for immersion objectives), in mount- 

 ing sections stained by Giemsa's 

 method, which is superior to balsam, 

 but it drys slowly and is not better than 

 clarite. Damar has been recommended 

 for stains likely to fade and colophonium 

 for thick sections of the nervous system 

 for which covers are not used; both 

 however appear to be less valuable than 

 clarite. 



Museum specimens require an aque- 

 ous mounting medium which preserves 

 colors. See Color Preservation. See 

 Plastics for museum work. 

 Mucicarmine for mucus, Mayer's (Mallory 

 and Parker in McClung, p. 417). To 



make up stain, mix carmine, 1 gm.; 

 aluminum chloride, 0.6 gm.; and aq. 

 dest., 2 cc. Heat over flame for 2 min. 

 Color of solution darkens. Add grad- 

 ually 100 cc. 50% ale. stirring constantly 

 until dissolved. After 24 hrs. filter. 

 Filtrate keeps well. Stain paraffin sec- 

 tions of absolute alcohol fixed tissue in 

 carmine sol. 5-10 min. Wash in water, 

 dehydrate, clear and mount. Mucus 

 is red. When nuclei also are colored red, 

 add few drops 1% aq. sodium bicarbon- 

 ate to the stain. It is customary to 

 stain cells and nuclei before hand with 

 alum hematoxylin. Bensley (Cowdry's 

 Special Cytology, 1932, p. 203) uses 

 alcoholic chrome sublimate (sat. mer- 

 curic chloride and potassium bichromate 

 in 95% ale.) and increases the content of 

 carmine 5 times. 



Mucigen, intracellular antecedent of Mucin. 



Mucihematein for mucus, Mayer's, Mal- 

 lory and Parker in McClung, p. 416). 

 Makeup: (A) hematein, 0.2 gm.; alumi- 

 num chloride, 0.1 gm.; glycerin, 40 cc; 

 aq. dest., 60 cc. and (B) hematein, 0.2 

 gm.; aluminum chloride, 0.1 gm.; 70% 

 alcohol, 70 cc; nitric acid, 1-2 drops. 

 A is advised except when the mucus 

 swells much in which case use B. 

 Stain paraffin sections of absolute alco- 

 hol fixed tissue 5-10 min. Wash in 

 water. Dehj-drate in 95% ale. and in 

 abs. Clear in xylol and mount in bal- 

 sam. Mucus stains blue. The other 

 materials are colorless. Preliminary 

 coloration with carmine is suggested. 

 Bensley (Cowdry's Special Cytology, 

 1932, p. 203) used alcoholic chrome sub- 

 limate fixation (sat. mercuric chloride 

 and potassium bichromate in 95% ale) 

 and increased the content of hematein 

 five times. 



Mucin, one of several glycoproteins found in 

 mucus. See Mucus and Mucicarmine, 

 Mucihematein and Mucisudan stains. 



Mucisudan is a dye of undetermined compo- 

 sition made by hydrolysis of sudan 

 black B with acetic acid and recom- 

 mended as a new stain for mucin (Leach, 

 E. H., J. Path, and Bact., 1938, 47, 

 637-639). 



Mucoproteins. A method for histological 

 distinction between the chondroitin 

 sulphuric acid protein of connective 

 tissue mucus and the mucotin sulphuric 

 acid protein of epithelial tissues has been 

 worked out by L. H. Hempelmann, Jr., 

 Anat. Rec, 1940, 78, 197-206. Briefly 

 stated toluidin blue in 1:280,000 will 

 stain the former vividlj' and the latter 

 not at all . 



Mucus means slime. It is a viscid, stringy 

 material which ordinarily stains with 

 basic dyes and is found in many parts of 

 the body. The chemical composition 



