Calbindin D28-like immunoreactivity during the formation of the enamel-free area in the rat molar teeth

Previous studies have demonstrated the presence of calbindin D28k in the am eloblasts derived from the inner enamel epithelium. The occlusal surfaces o f the rodent molars partly lack the enamel covering, which is referred to a s enamel-free area (EFA). In the present study, we compared the immunohisto chemical localization of calbindin D28k-like immunoreactivity (CB-LI) in th e cells at the EFA (FFA cells) and ameloblasts of the rat molar teeth at th e light microscopic level. CB-LI was strong in the ameloblasts of the prese cretory through the protective stages, while it was faint at the late secre tory to transitional stages. However, some mature ameloblasts lacked the im munoreactivity. On the other hand, the majority of EFA cells showed distinc t polarization and elongation that were absent in few cells at the early st age of EFA formation. At all stages, the EFA cells adjacent to the amelobla sts showed CB-LI, however, some cells adjacent to the mature ameloblasts la cked the reaction. Intensive CB-LI was demonstrated in EFA cells at the red uced enamel epithelium. These immunohistochemical findings suggest EFA cell s have cytochemical properties similar to those of ameloblasts. Anat Rec 25 8:384-390, 2000. (C) 2000 Wiley-Liss, Inc.