title: An immunohistochemical and ultrastructural study of the pericellular matrix of uneroded hypertrophic chondrocytes in the mandibular condyle of aged c-src-deficient mice.
abstract: OBJECTIVE
  Previous studies indicate that hypertrophic chondrocytes can transdifferentiate or dedifferentiate and redifferentiate into bone cells during the endochondral bone formation. Mandibular condyle in aged c-src-deficient mice has incremental line-like striations consisting of cartilaginous and non-cartilaginous layers, and the former contains intact hypertrophic chondrocytes in uneroded lacunae. The purpose of this study is to determine the phenotype changes of uneroded hypertrophic chondrocytes.
  
  
  METHODS
  Immunohistochemical and ultrastructural examinations of the pericellular matrix of hypertrophic chondrocytes in the upper, middle, and lower regions of the mandibular condyle were conducted in aged c-src-deficient mice, using several antibodies of cartilage/bone marker proteins.
  
  
  RESULTS
  Co-localisation of aggrecan, type I collagen, and dentin matrix protein-1 (DMP-1) or matrix extracellular phosphoprotein (MEPE) was detected in the pericellular matrix of the middle region. Ultrastructurally, granular substances in the pericellular matrix of the middle region were the remains of upper region chondrocytes, which were mixed with thick collagen fibrils. In the lower region, the width of the pericellular matrix and the amount of collagen fibrils were increased. Versican, type I collagen, DMP-1, and MEPE were detected in the osteocyte lacunae. Additionally, DMP-1 and MEPE were detected in the pericellular matrix of uneroded hypertrophic chondrocytes located in the lower, peripheral region of the mandibular condyle in younger c-src-deficient mice, but not in the aged wild-type mice.
  
  
  CONCLUSIONS
  These results indicate that long-term survived, uneroded hypertrophic chondrocytes, at least in a part, acquire osteocytic characteristics.
authors: Division of Histology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Tobetsu-cho, Ishikari-gun, Hokkaido, Japan. sshibata@hoku-iryo-u.ac.jp
authors: Shunichi
authors: S
authors: Shibata
authors: Otto
authors: O
authors: Baba
authors: Tsuyoshi
authors: T
authors: Oda
authors: Tamaki
authors: T
authors: Yokohama-Tamaki
authors: Chunlin
authors: C
authors: Qin
authors: William T
authors: WT
authors: Butler
authors: Yasunori
authors: Y
authors: Sakakura
authors: Yoshiro
authors: Y
authors: Takano
mesh_terms: D053674:Aggrecans / Q000032:analysis; D000375:Aging / Q000502:physiology*; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D019902:Chondrocytes / Q000473:pathology / Q000648:ultrastructure*; D024042:Collagen Type I / Q000032:analysis; D024043:Collagen Type II / Q000032:analysis; D024121:Collagen Type X / Q000032:analysis; D005109:Extracellular Matrix / Q000737:chemistry / Q000648:ultrastructure; D016326:Extracellular Matrix Proteins / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis; D006984:Hypertrophy; D007150:Immunohistochemistry; D008335:Mandibular Condyle; D051379:Mice; D008817:Mice, Mutant Strains; D046529:Microscopy, Electron, Transmission; D010750:Phosphoproteins / Q000032:analysis; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000172:deficiency*; D053675:Versicans / Q000032:analysis
chemical_list: D053674:Aggrecans; D015415:Biomarkers; D024042:Collagen Type I; D024043:Collagen Type II; D024121:Collagen Type X; C513308:Dmp1 protein, mouse; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C518716:Mepe protein, mouse; D010750:Phosphoproteins; D053675:Versicans; D016392:Proto-Oncogene Proteins pp60(c-src)