Electron microscopic studies on the potential loss of crystallites from routinely processed sections of young enamel in the rat incisor

Bishop, M. A.; Warshawsky, H.

doi:10.1002/ar.1092020202

Cited by 37 publications

(19 citation statements)

References 17 publications

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“…Ultrathin sections were cut with a diamond knife on a Reichert-Jung Ultracut OmU-4 counterstained with both uranyl acetate and lead citrate (routine thin sections) and/or only uranyl acetate (cytochemistry) before being examined in a Hitachi HU-12A electron microscope at an operating voltage of 75 kV. Ultrathin sections of undemineralized tissues were cut using ethylene glycol as trough fluid (Bishop and Warshawsky, 1982) and examined without counter staining. All chemical reagents for cytochemistry were purchased from Sigma Chemical.…”

Section: Acid Trimetaphosphatase Cytochemistrymentioning

confidence: 99%

Dentin resorption mediated by odontoclasts in physiological root resorption of human deciduous teeth

et al. 1988

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Extracted human deciduous teeth undergoing physiological root resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM) and analytical transmission electron microscopy, as well as acid trimetaphosphatase cytochemistry. The granulated tissues, which are rich in multinucleated odontoclasts and capillary vessels, formed various resorption lacunae on the resorbing dentin surfaces. SEM observations of dentin surfaces treated with sodium hypochlorite revealed two types of resorption lacunae: deep, round lacunae in which the peritubular matrix of dentinal tubules was strongly dissolved; and shallow, irregular lacunae with intact peritubular matrix. In trypsin-treated materials, the resorption surfaces were characterized by the presence of numerous collagen fibers in both the peritubular and intertubular matrices, suggesting demineralization of the surface dentin. Odontoclasts were characterized by the presence of abundant mitochondria, perinuclear stacks of Golgi membranes, various lysosomes, numerous endocytotic vacuoles, and a well-developed ruffled border against the resorption lacunae. Most endocytotic vacuoles were distributed in the cytoplasm between the ruffled border and the nuclei. In undemineralized ultrathin sections, the surface dentin of resorption lacunae consisted of collagen fibers and apatite crystals and had a lower packing density than those in unresorbed, deeper dentin. Many apatite crystals were demonstrated to be present in the extracellular channels of the ruffled border and in adjacent endocytotic vacuoles derived from it. Lysosomes located in the perinuclear cytoplasm of odontoclasts contained amorphous dense material and/or a small amount of crystals. An energy-dispersive x-ray microanalysis of apatite crystals in undemineralized sections indicated that the energy spectrum peaks of Ca and P detected from crystals in resorbing dentin were much lower than those in unresorbed dentin. Similarly, lower spectrum peaks of Ca and P were obtained from crystals found in the ruffled border and endocytotic vacuoles of odontoclasts. A slight trace Ca peak also was detected in the amorphous dense material in lysosomes of odontoclasts. The enzyme cytochemistry of lysosomal acid trimetaphosphatase indicated that odontoclasts had intense enzymatic activity in the Golgi membranes, endoplasmic reticulum cisternae, lysosomes, and endocytotic vacuoles. Dense reaction precipitates of enzymatic activity also were found along the dentin surfaces of resorption lacunae occupied by odontoclast ruffled borders.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Acid Trimetaphosphatase Cytochemistrymentioning

confidence: 99%

Dentin resorption mediated by odontoclasts in physiological root resorption of human deciduous teeth

et al. 1988

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“…This solution is rather acidic and, as a consequence, likely to dissolve part or all of the inorganic mineral crystals (Bishop and Warshawsky 1982;Bonucci et al 1988). The remaining structures which are identified in the TEM and referred to as crystal ghosts, consist of mineral-associated organic substances.…”

Section: Discussionmentioning

confidence: 99%

Light and electron microscopic morphology of the temporomandibular joint in growing and mature crab-eating monkeys (Macaca fascicularis): the condylar calcified cartilage

Luder

Schroeder

1992

Anat Embryol

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In an attempt to show maturational alterations in the calcified cartilage, mandibular condyles of four growing and four adult male monkeys (Macaca fascicularis) were studied using light microscopy as well as transmission and scanning electron microscopy. All specimens were initially fixed by perfusion in the presence of ruthenium red. For examination of the hard tissue surfaces in the scanning electron microscope, uncalcified tissues were removed with sodium hypochlorite. In growing animals, almost the entire hard tissue surface in the joint region of the condyle was formed by calcified cartilage, while in adult animals, calcified cartilage was confined to load-bearing regions. In growing animals, the appearance of the calcified cartilage surface suggested a continuously advancing mineralizing front similar to that seen in the epiphyseal plate. Chondrocytes mostly exhibited a terminal stage of hypertrophy, and seemed to die and get lost through vascular invasion and subsequent endochondral ossification. In adult animals, most of the calcified cartilage surface appeared comparatively stable, and resembled the tidemark of articular cartilage. Chondrocytes were usually small and appeared viable. However, on the adult condyles, there were always circumscribed islands where chondrocytes and the pattern of mineralization resembled those seen in growing animals. In these regions, prominent chondroclastic activity indicated extensive articular remodelling. These observations suggest that at the end of somatic growth, condylar calcified cartilage undergoes considerable maturation from a type reminiscent of hyaline growth cartilage to a type resembling articular cartilage. Concomitantly, chondrocytes appear to change their developmental program, in that they stop enlarging and lose their commitment to death. However, they may be able to retain, or switch back to, a more immature stage, in case there is need for extensive articular remodelling.

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“…For light microscopic observation, serial semithin sections (2 µm) were cut with a diamond knife on an RMC MT-6000 Ultramicrotome and stained with toluidine blue. For transmission electron microscopic observation, ultrathin sections of the undecalcified specimens were cut with a diamond knife by using ethylene glycol as trough fluid (Bishop and Warshawsky, 1982) and were collected on Formvar-coated, copper grids. They were examined in a JEOL-1200EX electron microscope at 80 kV or 100 kV with or without counterstaining.…”

Section: Undecalcified Teethmentioning

confidence: 99%

Ultrastructural features of odontoclasts that resorb enamel in human deciduous teeth prior to shedding

et al. 1998

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Three dental hard tissues, i.e., cementum, dentin, and enamel, are resorbed by multinucleated cells referred to as "odontoclasts." These cells have morphological and functional characteristics similar to those of bone-resorbing osteoclasts. However, concerning enamel resorption, which is a process that may occur during tooth eruption, satisfactory ultrastructural data on odontoclastic resorption are still lacking. Ultrastructural and histochemical characteristics of odontoclasts resorbing enamel of human deciduous teeth prior to shedding were examined by means of light microscopy and transmission and scanning electron microscopy. Odontoclasts that that resorbed enamel were tartrate-resistant acid phosphatase (TRAP)-positive multinucleated giant cells that were essentially the same as those that resorbed dentin and cementum. Ultrastructurally, they had numerous mitochondria, lysosomes, and free polysomes in their cytoplasm. In addition, they were characteristically rich in large cytoplasmic vacuoles containing enamel crystals in the cytoplasm opposite the ruffled border. Although they extended a well-developed, ruffled border against enamel surface, a clear zone--an area typically devoid of organelles--was rarely seen in these cells. In many cases, the cells were in very close contact with the enamel surface by the peripheral part of their cytoplasm. The enamel prisms at the resorption surface contained more loosely packed and electron-lucent enamel crystals compared with those of unresorbed, intact enamel. Furthermore, numerous thin needle- or plate-like enamel crystals that were liberated from the enamel matrix were found in the extracellular channels of the ruffled border and in various-sized cytoplasmic vacuoles in their cytoplasm. The superficial layer of the enamel matrix undergoing odontoclastic resorption stained positively with toluidine blue and for TRAP activity. The results of the present study suggest that odontoclasts resorbing enamel secrete acids as well as organic components, including hydrolytic enzymes, into the resorption zone underlying their ruffled border and that they phagocytose crystals that have been liberated from the partially demineralized enamel matrix by acids, subsequently dissolving them intracellularly.

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Electron microscopic studies on the potential loss of crystallites from routinely processed sections of young enamel in the rat incisor

Cited by 37 publications

References 17 publications

Dentin resorption mediated by odontoclasts in physiological root resorption of human deciduous teeth

Dentin resorption mediated by odontoclasts in physiological root resorption of human deciduous teeth

Light and electron microscopic morphology of the temporomandibular joint in growing and mature crab-eating monkeys (Macaca fascicularis): the condylar calcified cartilage

Ultrastructural features of odontoclasts that resorb enamel in human deciduous teeth prior to shedding

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