Alkaline Phosphatase in Pulpal Tissue of Human Teeth

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Abstract
This investigation is concerned with the histochemical localization of alkaline phosphatase in sections of decalcified and undecalcified teeth obtained from a human term fetus. Transverse sections cut at the cervical end of the developing crown of a deciduous canine were subjected to modified Gomori technic (''43) for the demonstration of the enzyme in undecalcified material. By employing a slightly modified Lorch (''46) method, other teeth were decalcified for periods of 9, 12, 16, and 23 days, respectively, and the enzyme reactivated prior to its demonstration by the Gomori method. Decalcification was carried out in a mixture of acetic acid and Na acetate, each 0. 2_N, which was adjusted to a pH of 4. 5 and to which 0.004 g. of ZNSO4 was added for each 500 cc. of soln. The enzyme was reactivated by incubating the decalcified specimens for 2-4 hrs. at 37[degree]C in a mixture of 2 vol. of 0.075% glycine and 1 vol. of 1% Na barbital. In regions where dentinogenesis is in progress or is imminent, the sites of greatest enzyme localization are in the odontoblastic and subodontoblastic regions as well as in the odontoblasts themselves. The intensity of the phosphatase reaction is inversely related to the duration of decalcification. The process of decalcification and reactivation alters the precise localization of the enzyme.