ENZYME HISTOCHEMISTRY OF THE PRENATAL DEVELOPMENT OF HUMAN DECIDUOUS TEETH

Publisher Website
Google Scholar
Abstract
Enzyme histochemical studies were performed on tooth germs from 30 human fetuses. The investigation comprises the period from bud stage to bell stage with incipient mineralization and is distributed according to crown-rump length from 24.5 mm to 230 mm (8th to 26th week). Histochemical reactions (azo dye) were carried out for demonstrating alkaline phosphatase, acid phosphatase, and unsepcific AS-esterase. In the cap and bell stages the activity of alkaline phosphatase was most pronounced in the reticular layer and stratum intermedium of the enamel organ, while no activity was found in the ameloblastic layer. The odontoblasts contain alkaline phosphatase, and the activity is localized mainly to the cell membrane from which it could be traced into he fibre of Tomes. Acid phosphatase and unspecific AS-esterase were demonstrated in odontoblasts as well as ameloblasts. At the onset of enamel formation the reaction in the ameloblasts became accentuated. The enzyme activity of acid phosphatase as well as of unspecific AS-esterase was particularly distinct in Tomes'' process. Apart from the odontoblastic processes in predentin and dentin, there was no activity of the above-mentioned enzymes In predentin, dentin, or enamel. Owing to a high activity of acid phosphatase and especially of unsepcific AS-esterase, histiocytes were demonstrated in the dental papilla, along the outer enamel epithelium, and in the reticular layer. The histiocytes in the last-mentioned area had migrated down through the outer enamel epithelium. Various theories advanced concerning the biological role of the named enzymes in the differentiation, matrix formation, and mineralization in tooth germs were also discussed.