Studies about the specificity of the histochemical localization of choline acetyltransferase.

1. Tissues examined for the histochemical localization of choline acetyltransferase are best fixed by acetone. 2. Topographical identification of choline acetyltransferase by its reaction products is not only substrate-dependent because a slight staining also occurred in the absence of the substrates choline and acetyl-coenzyme in the incubation medium. 3. Histochemical localization of choline acetyltransferase was inhibited by sarin but not by DFP or eserine. 4. According to Burt and Silver's method cells and cell organelles, of which the enzymatic content is doubtful, where stained. 5. Chloroacetylcholine-perchlorate did not inhibit the histochemical localization of choline acetyltransferase. 6. The staining of acetylcholinesterase showed a different topographical distribution although both methods were inhibited by sarin.