"Acid Phosphatase" Reactions in Peripheral Nerves

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Abstract
The acid phosphatase reaction of Gomori was studied in peripheral nerves. Acetone-fixed nerves were teased in 80% alc. and placed in glycerophosphate-lead reagent buffered at pH 4.8 with molar acetate. After 2-18 hrs. at 38[degree] C they were washed and the lead visualized with ammonium sulphide. The peripheral stump of a cat''s sciatic nerve after transection appeared grossly to be as intensely stained as the central stump. Microscopically, the fibers of the latter showed precise staining of the axons, and nuclei could rarely be demonstrated. Peripherally, where invasion of regenerating fibers was prevented, all types of nuclei reacted strongly, as did degenerating axons and myelin. When strands of these nerves were extracted with water either before or after glycerophosphate-lead treatment, the nuclei were first to suffer. After 16-24 hrs., which left the axons stainable, the nuclei no longer reacted. Water extractions indicated that both enzymes and lead phosphate could readily be removed from the tissue, suggesting that both moved freely in the tissue. Thus the Gomori method was unreliable for localization of acid phosphatase. When normal fresh nerves were placed directly in glycerophosphate-lead reagent, various types of nuclei were the dominant features. After 25 mins.'' incubation at 38[degree] C an occasional nucleus appeared and some Schwann cell cytoplasmic granules were stained. At 45 mins. practically all sheath cell nuclei were filled with granules, smaller than the nucleolus, which was darker. In the cat, the Schwann cell cytoplasm developed a dark tinge in addition to the granules in 18-24 hrs. of incubation. Another reaction in fresh tissue was that the axon ends reacted intensely to injury. If dry ice was applied to a living nerve, all axons were shriveled. When the tissue was thawed in chilled glycerophosphate-lead reagent and then incubated, all axons were as intensely stained as in acetone-fixed material, and all nuclei reacted as in fresh tissue. The findings in general indicated that the histologic acid-phosphatase reactions were unreliable.