DIFFERENTIAL SPATIOTEMPORAL EXPRESSION OF E-CADHERIN AND P-CADHERIN DURING MOUSE TOOTH DEVELOPMENT

Changes in E- and P-cadherin (E- and P-CD) expression during embryonic mouse first molar development were analyzed by immunohistochemistry. During the induction and morphogenesis stages (bud, cap and early bell stages), E-CD was expressed in the cells of the invaginating epitheli al tooth bud and in the cells of the outer enamel epithelium, stellate reticulum and stratum intermedium, suggesting a role for this molecul e in the maintenance of enamel organ architecture. On the other hand, P-CD was strongly expressed in the inner enamel epithelium suggesting its participation in the processes of mesenchymal induction. During th e cytodifferentiation stage (late bell stage), E-CD was expressed in p olarizing preameloblasts. but cadherin expression was restricted to th e basal and apical poles of differentiated secretory ameloblasts, wher e the zonula adherens type of cell-cell junctions is located. The pres ent study demonstrates for the first time the spatiotemporal expressio n of cadherins during tooth development and suggests differential and specific roles for E-CD and P-CD during the morphogenesis and cytodiff erentiation processes of this organ.