Caspase 3 activation in the primary enamel knot of developing molar tooth.

Mammalian teeth develop during embryogenesis as epithelio-mesenchymal organs. The primary enamel knot is considered as a signaling center in tooth morphogenesis. After tooth bell formation, this epithelial structure undergoes apoptosis. Activation of caspase 3 represents a crucial step in the intracellular death machinery. Procaspase 3 and caspase 3 molecules were localized in the primary enamel knot of the field vole using immunohistochemistry. Different fixation procedures in cryopreserved and paraffin-embedded tissues and detection systems based on peroxidase and alkaline phosphatase mediated color reactions were applied. Apoptosis was detected using morphological criteria and the TUNEL assay. Procaspase 3 was found in both the epithelial and mesenchymal part of the tooth germ. Active caspase 3 was localized particularly in the primary enamel knot, its distribution correlated with dental apoptosis and showed a similar pattern in the field vole as in the mouse.