title: Recruitment of osteoclasts in the mandible of osteopetrotic (op/op) mice.
abstract: Osteoclasts in osteopetrotic (op/op) mice are substantially reduced by the absence of functional activities of macrophage colony-stimulating factor (M-CSF). However, it is known that osteoclasts appear in op/op skeletal bones with aging, although the molecular mechanism for this is unknown. In order to investigate osteoclastic recruitment in the jaw bones of op/op mice, osteoclastic distribution was analysed for 2 yr after birth by histochemistry for tartrate-resistant acid phosphatase activity and immunohistochemistry for cathepsin K. Osteoclasts in op/op mandibular bones decreased rapidly in number after birth and disappeared by 3 d, although there was no difference in the osteoclastic distribution between op/op and normal littermates at birth. At 2 wk, osteoclasts began to reappear around op/op tooth germs, where no apparent connective tissue layer intervened between tooth germs and bone trabeculae. They increased in number and were scattered over the mandible, reaching a maximum at 8 wk, when periodontal ligament-like structures were recognizable around incisor germs. Osteoclasts then again decreased gradually, and after 62 wk few osteoclasts were seen in op/op mandibular bones, whose marrow space disappeared. These findings suggest that osteoclasts are recruited in an M-CSF-independent manner in op/op mandibles, especially in areas around tooth germs.
authors.affiliation: Department of Oral Pathology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ida-Yonemochi
authors.forename: Osamu
authors.initials: O
authors.lastname: Ishibashi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Sakai
authors.forename: Takashi
authors.initials: T
authors.lastname: Saku
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000375:Aging / Q000473:pathology; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001853:Bone Marrow / Q000473:pathology; D056657:Cathepsin K; D002403:Cathepsins / Q000032:analysis; D002452:Cell Count; D003546:Cysteine Endopeptidases / Q000032:analysis; D007180:Incisor / Q000473:pathology; D007527:Isoenzymes / Q000032:analysis; D008334:Mandible / Q000473:pathology*; D051379:Mice; D008815:Mice, Inbred Strains; D009154:Mutation / Q000235:genetics; D010010:Osteoclasts / Q000473:pathology*; D010022:Osteopetrosis / Q000235:genetics / Q000473:pathology*; D010513:Periodontal Ligament / Q000473:pathology; D018807:Polymorphism, Single-Stranded Conformational; D000071681:Tartrate-Resistant Acid Phosphatase; D014083:Tooth Germ / Q000473:pathology
chemical_list: D015415:Biomarkers; D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D056657:Cathepsin K; C534132:Ctsk protein, mouse