Matrix - Mineral Relationships in Enamel Tissues

Fearnhead, R.W.

doi:10.1177/00220345790580024501

Cited by 46 publications

(31 citation statements)

References 22 publications

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“…Several studies suggested that elasmobranch enameloid was the primitive hard tissue that appeared before enamel and that the relationship between the two is directly homologous (Fearnhead, 1979;Goto, 1976Goto, , 1987Moss, 1970Moss, , 1977. In contrast, it was suggested that elasmobranch enameloid is distinct from enamel and that the enameloid found in living fish is not an ancestral hard tissue of enamel, but rather an analog (e.g., Sasagawa and Ishiyama, 1999).…”

Section: Relationship Between Enameloid and Enamelmentioning

confidence: 99%

Mineralization patterns in elasmobranch fish

Sasagawa

2002

Microscopy Res & Technique

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This article reviews current findings on the organic matrix and the mineralization patterns in elasmobranchs, including an analysis of the role of the dental epithelial cells and the odontoblasts during odontogenesis. Our electron micrographs demonstrated that tubular vesicles limited by a unit membrane occupied the bulk of the elasmobranch enameloid matrix during the stage of enameloid matrix formation. It is likely that the tubular vesicles originated from the odontoblast processes. Two types of electron-dense fibrils, with cross-striations at intervals of approximately either 17 nm or 55 nm, respectively, were detected in the enameloid matrix. These data suggest that odontoblasts were strongly involved in enameloid matrix formation and in initial enameloid mineralization. Two types of odontoblasts, dark and light cells, were recognized during the stage of dentinogenesis. The light cells contained numerous mitochondria, intermediate filaments, and microtubules that extended their processes into the dentin. The dark cells possessed a well-developed Golgi apparatus and many cisternae in the rough endoplasmic reticulum, which suggests that the dark cells are involved in the formation of dentin. The inner dental epithelial (IDE) cells exhibited a well-developed Golgi apparatus, many mitochondria, cisternae of smooth endoplasmic reticulum, vesicles, vacuoles, and granules during the mineralization and maturation stages. During the stages of mineralization and early maturation, ACPase-positive granules were visible in the IDE cells and ALPase and Ca-ATPase activities were found at the lateral and proximal cell membrane of the IDE cells, suggesting that the IDE cells are involved in the removal of enameloid organic matrix and in the process of mineralization during later stages of enameloid formation. Our data indicate that elasmobranch enameloid is distinct from teleost enameloid, based on its organic content, on the mechanisms of its mineralization, and on the role of IDE cells concerning enameloid formation.

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Section: Relationship Between Enameloid and Enamelmentioning

confidence: 99%

Mineralization patterns in elasmobranch fish

Sasagawa

2002

Microscopy Res & Technique

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“…T he function of enam el m a trix is p ro b ab ly m ore com plex as, due to the fact th at only b ru sh ite nuclei are fo rm ed , this m atrix m ust at least inhibit th e form ation of O C P nuclei from the enam el fluid which is su p e rsa tu rate d b o th with O C P and w ith bru sh ite. C ertainly, th e en am el m atrix allows for the form ation of the needle-like brushite crystals [43][44][45] in p ro b ab ly the sam e way as colla gen allows for O C P nu cleatio n , i.e. it acts prim arily as a m echanical b arrier leading to a lim ited form and size of th e crystals [43] ra th e r than as an agent p ro m oting th e h etero g en eo u s nucleation of brushite.…”

Section: Discussionmentioning

confidence: 99%

“…C ertainly, th e en am el m atrix allows for the form ation of the needle-like brushite crystals [43][44][45] in p ro b ab ly the sam e way as colla gen allows for O C P nu cleatio n , i.e. it acts prim arily as a m echanical b arrier leading to a lim ited form and size of th e crystals [43] ra th e r than as an agent p ro m oting th e h etero g en eo u s nucleation of brushite. In any w ay, th e m ost p red o m in an t role of the m atrix seem s to be th a t of a spatial constriction and o rien tatio n .…”

Section: Discussionmentioning

confidence: 99%

On the Possible Relation between Morphology and Precursors of the Crystallities in Calcified Tissues

Driessens¹,

Terpstra²,

Bennema³

et al. 1987

Zeitschrift Für Naturforschung C

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Crystal M orphology, Precursors, BiomineralsCrystal structure data on hydroxyapatite, octocalcium phosphate and brushite have been used in order to predict their crystal morphology on the basis of the H artm an-Perdok theory. The predicted forms are pencil-like for hydroxyapatite, board-like for octocalcium phosphate and flattened needle-like for brushite. Although the biominerals in bone, dentine and tooth enamel have an apatite structure, their form is not pencil-like. This may partially be due to the fact that precursor phases are nucleated first in these tissues during mineralization and that these precursor phases are transform ed later by topotactical reactions into compounds with apatite structure or that they serve as nuclei for ongrowth of apatite. The form of the mineral particles in m ature bone and dentin is board-like which indicates that octocalcium phosphate might be their precursor phase. H owever, the form of the crystals in mature enamel is flattened needle-like which indicates that brushite is their precursor phase. It is argued that a possible difference in the nature of the precursor phase may be due primarily to differences in the cellular activities of the odontoblasts and osteoblasts as compared to those of the ameloblasts, and secondarily to matrix effects. In both cases, however, the main effect of the matrix seems to be that it acts as a mechanical barrier leading to a limited form and size and, of course, a certain orientation of the crystals, rath er than as an agent for heterogeneous nucleation. The validity of the present considerations depends as yet on the assumption that the ions and molecules occurring in body fluids do not dom inate the habit of calcium phosphate crystals.

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“…The resultant of these features provide for species-specific enamel crystal patterns in enameloid of sharks and bony fishes as well as the enamel of newts, crocidiles, rabbits, and mice (Boyde, 1995;Greenberg et al, 1983;Kawasaki and Fearnhead, 1983). Arguably, although the morphological phenotype of enamel varies between species, a common plan of developmental processes and their control are present within all vertebrate species that express enamel organ epithelial-derived extracellular matrix formation (see Fearnhead, 1979;Kallenbach and Piesco, 1978;Osborn, 1973;Piesco, 1979;Piesco and Kallenbach, 1985).…”

Section: Phylogenetic Features Of Enameloid and Enamel Biomineralizatmentioning

confidence: 99%