title: Immunolocalization of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in Meckel's cartilage compared with developing endochondral bones in mice.
abstract: We examined the immunolocalization of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in areas of resorption caused by osteoclasts/chondroclasts on embryonic days 14-16 (E14-16) in Meckel's cartilage, and compared the results with those in endochondral bones in mice. Intense RANKL and OPG immunoreactivity was detected in the chondrocytes in Meckel's cartilage. On E15, when the incisor teeth were closest to the middle portion of Meckel's cartilage, tartrate-resistant acid phosphatase (TRAP)-positive cells appeared on the lateral side of the cartilage. Furthermore, the dental follicle showed moderate immunoreactivity for RANKL and OPG, whereas osteoblasts derived from perichondral cells were immunonegative for RANKL and OPG in that area. On E16, cartilage resorption by TRAP-positive cells had progressed at the differential position, and intensely immunoreactive products of RANKL were overlapped on and found to exist next to TRAP-positive cells in the resorption area. In developing metatarsal tissue, OPG immunoreactivity was intense in periosteal osteoblasts, whereas RANKL was only faintly seen in some of the periosteal cells. In epiphyseal chondrocytes of the developing femur, RANKL immunoreactivity was moderate, and OPG scarcely detected. These results indicate a peculiarity of RANKL and OPG immunolocalization in resorption of Meckel's cartilage. Growth of the incisor teeth may be involved in the time- and position-specific resorption of Meckel's cartilage through local regulation of the RANKL/OPG system in dental follicular cells and periosteal osteoblasts, whereas RANKL and OPG in chondrocytes seem to contribute to resorption through regulation of the chondroclast function.
authors.affiliation: Department of Oral Anatomy, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, Japan. yasaka@hoku-iryo-u.ac.jp
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Sakakura
authors.forename: Eichi
authors.initials: E
authors.lastname: Tsuruga
authors.forename: Kazuharu
authors.initials: K
authors.lastname: Irie
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Hosokawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yajima
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001842:Bone and Bones / Q000737:chemistry* / Q000196:embryology*; D002352:Carrier Proteins / Q000032:analysis*; D002356:Cartilage / Q000737:chemistry* / Q000196:embryology*; D019902:Chondrocytes / Q000737:chemistry; D005260:Female; D047109:Fetal Development; D006023:Glycoproteins / Q000032:analysis*; D006614:Hindlimb; D007150:Immunohistochemistry / Q000379:methods; D007180:Incisor; D008334:Mandible; D008562:Membrane Glycoproteins / Q000032:analysis*; D051379:Mice; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis*; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis*
chemical_list: D015415:Biomarkers; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse