2002 Volume 22 Issue 2 Pages 130-136
Receptor activator of NFkB ligand, RANKL, is one of the key regulatory molecules in osteoclast formation and functions. The authors examined the RANKL localization in the periodontal tissues during experimental movement of rat molars. To produce orthodontic force, an elastic band was inserted between the upper first and second molars for 4 days, and the dissected maxillae were subjected to light and electron microscopic immunocytochemical examination for RANKL. Expression of RANKL protein was detected in osteoblasts, osteocytes, fibroblasts, and osteoclasts mostly located in resorption lacunae. In osteoblasts, osteocytes, and fibroblasts, RANKL localization was mainly observed in the cytoplasm, the cisterns of rough-surfaced endoplasmic reticulum and along the plasma membranes. In osteoclasts, RANKL was expressed along the ruffled border membranes and in the cytoplasm including that of the clear zone. These results suggest that during tooth movement, osteoclast differentiation and activation are regulated, at least in part, by RANKL, possibly produced by osteoblasts/stromal cells and osteoclasts themselves in the periodontal tissues.
