402 Special Procedures III (chap. 24) 



than is true of other plastics. The required sokitions can be obtained as 

 a Cargille (Nysem) Epoxy Embeclcling Kit from Cargille Sons, Little 

 Falls, N.J. Ftill directions for use are enclosed with the kit. (Also see 

 Richardson et al., 1960) 



Pease {I960) disagrees with the above, saying that the epoxy resin 

 forms brittle blocks, causing cutting artifacts and producing poor con- 

 trast in some specimens. Biological systems should be "stained" when 

 embedded in it. "Epon" epoxy resins are being developed; at the pres- 

 ent he prefers methacrylate embedding, although the methacrylate de- 

 composes inider electron bombardment. 



Butyl Methacrylate Embedding (newman, borysko, 

 and swerdlow, 1949) 



method: 



1. From fixative, quick rinse in salt solution or veronal buffer such as 

 fixative ions prepared in. 



2. Dehydrate in 50, 75, and 95% alcohol: 3-5 minutes each. Several 

 changes of absolute alcohol, at least 2 changes: 5-10 minutes; 1 

 chanoe: 15-20 minutes. 



3. Transfer to equal volumes of absokite ethyl alcohol and ?7-butyl 

 methacrylate monomer^: abotit 1 hotir. 



4. Transfer to monomer (no catalyst) 3 changes: 1 hour each. 



5. Set body of #00 gelatine capsule upright in wooden block or other 

 base. Fill with monomer plus 1% (by weight) of catalyst (2,4-di- 

 chlorobenzoyl peroxide^). Orient tissue in it and slip on lid. 



6. Place in oven, 45-50°C. Important that capsule be heated evenly 

 over entire surface. Suspend ^vith cellophane tape from rod or 

 other stipport inside oven. AVithin 6-8 hours a solid matrix of pol- 

 ymerized monomer has formed. Additional period of several hours 

 insures complete polymerization. 



7. Soak in water and peel off capsule. 



comments: 



The w-butyl methacrylate contains an inhibitor ^vhich must be re- 

 moved by repeated washings in a separatory ftmnel with dilute aque- 

 ous sodium carbonate until no color is visible in the ^vashings. Follow 

 with calcium chloride to remove the water. Keep in the refrigerator 

 to inhibit polymerization. Do not use rubber or plastic container for 

 storing. 



^ Rohm and Haas Co., Philadelphia. 



"Lucidol Division, Novadel-Agene Corporation, Buffalo. 



