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  • 2000-2004
  • 1990-1994  (2)
  • 1992  (2)
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  • 2000-2004
  • 1990-1994  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral pathology & medicine 21 (1992), S. 0 
    ISSN: 1600-0714
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Nucleolar organizers are major sites of ribosomal RNA synthesis and provide an index of transcriptional activity. In order to further define growth hormone actions on nucleolar organizer regions in tooth forming cells, hypophysectomized rats treated with growth hormone for 4 and 24 h, hypophysectomized and sham-operated animals were used. After demineralization and standard paraffin embedding, longitudinal sections of maxillary incisors were stained by a silver stain technique to reveal nucleolar organizer regions. The area of these regions per nucleus was measured using a modified microdensitometer. Analyses of variance of the resulting data showed that preameloblasts and preodontoblasts have greater silver stained nucleolar organizer region values than ameloblasts and odontoblasts. Hypophysectomy reduced and growth hormone partly restored the level of nucleolar organizer regions in preameloblasts and preodontoblasts, but not in mature ameloblasts or odontoblasts. In the case of the younger preameloblasts and preodontoblasts, the effect of growth hormone was seen within 4 h of growth hormone injection. In conclusion, rRNA synthesis, as revealed by the specific silver staining of nucleolar organizer regions in tooth forming cells, appears to be regulated by growth hormone over a relatively short time frame.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0827
    Keywords: Growth hormone ; Growth hormone receptor ; Odontogenesis ; Bone remodeling ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Growth hormone (GH) may regulate tooth formation and bone remodeling associated with tooth eruption. This study reports the distribution of growth hormone receptor/binding protein in developing rat molars and adjacent alveolar bone by immunocytochemistry using well-characterized anti-growth hormone receptor monoclonal antibodies. These tissues represent an excellent model for studying the ontogenic changes that occur in odontogenic and osteogenic cells, as these cells are found in linear arrays displaying the various stages of morphological and functional differention, and differentiated function. Immunoreactivity was first seen in precementoblasts in contact with the epithelial root sheath, and preodontoblasts. However, growth hormone receptor immunoreactivity was associated primarily with the cytoplasm of odontogenic and osteogenic cells forming their respective matrices. Thus, cementoblasts and odontoblasts at sites of new matrix formation showed intense immunoreactivity whereas cementocytes and mature odontoblasts at later stages of tooth development were nonreactive. Osteoblasts engaged in intramembranous ossification in the alveolar bone were positive, although osteocytes and endosteal cells were immunonegative. Osteoclasts at sites of alveolar bone remodeling resorption were also immunopositive. These patterns of receptor expression parallel the ontogenic sequences of odontogenic and osteogenic cells and suggest that GH promotes the functional state of these cells. Our results also imply that GH may influence differentiation or differentiated functions associated with odontogenesis, osteogenesis, and bone remodeling independent of systemic insulin-like GF-I.
    Type of Medium: Electronic Resource
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