Histochemical demonstration of acid phosphatase in hard tissues.

The action of the following decalcifying solutions for the demonstration of acid phosphatase has been studied: buffer solution acetic-acetate 0.05 M, pH 5; 2, 5, 10, 20, and 50% formic acid and 20% sodium citrate in equal parts (pH 2.6, 3, 3.8, 4.2, and 5); 0.5 M citric acid-NaOH, pH 4.2; Versene solution, 5%, pH 7. A comparative study of fixatives has been made also (neutral formalin, 10-20%; formalin-chloral hydrate (Fishman), acetone and 80% alcohol). The best results were obtained with fixation at 4°C in 10-20% neutral formalin or formalin-chloral hydrate, for a period of 24 hr, and decalcification with 20% sodium citrate, 5% formic acid, in equal parts, pH 4.2, which can act on both specimens or sections for a period up to 2 wk with very little loss of enzyme. It is not necessary to reactivate the enzyme after decalcification; frozen sections should be used and should be washed in distilled water before proceeding with the demonstration of the enzyme (Gomori's method or azo dye coupling). Other fixat...