The stainability of nerve fibers by protargol with various fixatives and staining technics

The influence of the commonly used tissue fixing reagents, individually and in various combinations, on subsequent staining by protargol was studied. The reagents used were formalin, formamide, picric acid, acetic acid, paranitrophenol, pyridine and chloral hydrate. Parraffin sections from intestine and peripheral nerve of cat, dog, monkey and rat were stained with protargol after fixation in various experimental mixtures of the fixing reagents. Satisfactory nerve stains of intestine were not obtained with regularity after any one fixing and staining procedure. (Good fixation and staining appeared to be influenced by properties inherent in the tissue itself and showed marked variations from animal to animal even in the same species.)Stains of nerve fibers in peripheral nerve trunks were much more easily obtained than in the intestine where good stains were sporadic and unpredictable. The use of a mixture of 0.5% protargol and 0.1% fast green FCF, is proposed as a silver-dye staining medium.