Chapter § 



Specialized Embedding 



Technics 



Water-Soluble Wax Embedding and Sectioning 



The so-called carbowax compounds and \vater-soluble polyethylene 

 glycol waxes, a series of polymers (compounds composed of the same 

 kind of atoms in the same percentage composition but in different 

 numbers and therefore having different molecular weights), each of 

 which is designated by its average molecular weight. These waxes are 

 used Avhen it is necessary to go directly from fixative or water to the 

 embedding medium; no alcohols or clearing agents are required. 



The following compounds are manufactured by the Carbide and 

 Carbon Chemicals Company: Compound 4000 is hard and dry, in crys- 

 talline flakes; Compound 1540 is not so firm, and will liquefy within a 

 week; Compound 1000 comes in slippery lumps and liquefies within 

 24 hours; Compound 1500 is a blend of equal parts of polyethylene 

 glycol 300 (a fluid) and wax 1540. 



Other carbowax compounds are the polyglycols E9000, E6000, 

 E4000, E2000, and El 000 manufactured by Doio Chemical Company, 

 and HEM [Harleco Embedding Media) by Hartman-Leddon Company. 



Wade (1952) finds 4000 too hard for his use and suggests a mixture of 

 1:9 or 2:8 of 1540 and 4000 depending upon weather, and recommends 

 the latter except in the hottest and most humid climate. 



Fixation: any fixative, but after a potassium dichromate fixative wash 

 for 12 hours before embedding^. 



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