Immunohistochemical study of structural proteins in developing junctional epithelium.

The objective of this study was to investigate structural proteins of ameloblasts, reduced enamel epithelium and junctional epithelium using antikeratin antibodies to determine if keratin expression changes as ameloblasts differentiate to cells of junctional epithelium. Block sections of fully erupted, partially erupted and unerupted molar and incisor teeth were removed at necropsy from monkeys age 2, 5, 6 and 7 years. Tissues were fixed in Carnoy's fixative, decalcified in Kristensen's solution for 4 to 8 weeks, embedded in paraffin and sectioned at 5 mu. Representative sections were stained with hematoxylin and eosin. Remaining sections were stained with antikeratin antibodies AE1, AE3, 34 beta E12, 35 beta H11 and anti-40kD using the avidin-biotin-conjugated immunoperoxidase method. Results were analyzed qualitatively for presence or absence of staining products. Antibody 35 beta H11 reacted with ameloblasts and reduced enamel epithelium during the early maturation phase of tooth development but not with the reduced enamel epithelium of erupting teeth or with junctional epithelium. The anti-40kD antibody stained ameloblasts and reduced enamel epithelium of unerupted teeth and teeth erupting through oral epithelium; however, junctional epithelium of partially erupted and fully erupted teeth were unstained. Antibodies AE1, AE3 and 34 beta E12 stained ameloblasts and all layers of reduced enamel epithelium and junctional epithelium in all stages of development. These results suggest a relationship between expression of structural proteins and changes during development and differentiation of ameloblasts to junctional epithelial cells.