Light and TEM study of nonregenerated and experimentally regenerated scales of <i>Lepisosteus oculatus</i> (holostei) with particular attention to ganoine formation

Sire, Jean‐Yves

doi:10.1002/ar.1092400206

Cited by 60 publications

(82 citation statements)

References 22 publications

(43 reference statements)

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“…Although our finding is somewhat surprising, an examination of enamel throughout evolution lends support to our discovery. Holostean fish, a member of a group of primitive bony fishes, can form ganoine that has been identified as true enamel on bony scales (Donoghue et al, 2006;Sire, 1994), consistent with our conclusion that the presence of ectopic bone in the dentin-forming site substitutes for dentin to induce ameloblast differentiation. From a regenerative medicine perspective, our study might provide useful future strategies for enamel regeneration.…”

Section: Ameloblast Differentiation Is Independent Of Odontoblast Difsupporting

confidence: 89%

SMAD4-mediated WNT signaling controls the fate of cranial neural crest cells during tooth morphogenesis

Huang

et al. 2011

Development

102

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SUMMARYTGF/BMP signaling regulates the fate of multipotential cranial neural crest (CNC) cells during tooth and jawbone formation as these cells differentiate into odontoblasts and osteoblasts, respectively. The functional significance of SMAD4, the common mediator of TGF/BMP signaling, in regulating the fate of CNC cells remains unclear. In this study, we investigated the mechanism of SMAD4 in regulating the fate of CNC-derived dental mesenchymal cells through tissue-specific inactivation of Smad4. Ablation of Smad4 results in defects in odontoblast differentiation and dentin formation. Moreover, ectopic bone-like structures replaced normal dentin in the teeth of Osr2-IresCre;Smad4 fl/fl mice. Despite the lack of dentin, enamel formation appeared unaffected in Osr2-IresCre;Smad4 fl/fl mice, challenging the paradigm that the initiation of enamel development depends on normal dentin formation. At the molecular level, loss of Smad4 results in downregulation of the WNT pathway inhibitors Dkk1 and Sfrp1 and in the upregulation of canonical WNT signaling, including increased -catenin activity. More importantly, inhibition of the upregulated canonical WNT pathway in Osr2-IresCre;Smad4 fl/fl dental mesenchyme in vitro partially rescued the CNC cell fate change. Taken together, our study demonstrates that SMAD4 plays a crucial role in regulating the interplay between TGF/BMP and WNT signaling to ensure the proper CNC cell fate decision during organogenesis.

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Section: Ameloblast Differentiation Is Independent Of Odontoblast Difsupporting

confidence: 89%

SMAD4-mediated WNT signaling controls the fate of cranial neural crest cells during tooth morphogenesis

Huang

et al. 2011

Development

102

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“…All three tissues are involved in odontogenesis in extant and extinct vertebrates, are neural crest derived, and can often occur together with enamel/enameloid as a result of epithelialê ctomesenchymal interaction. Enamel overlying dentine is a pattern characteristic of the vertebrate dermal skeleton and, contrary to Kemp & Nicoll (1995a) and Schultze (1996), enamel overlying bone is not unparalleled among the vertebrates (Smith 1979;Sire 1994). Although hypothetically possible, no examples have been reported where enamel can be observed directly overlying cartilage.…”

Section: (B) Basal Bodymentioning

confidence: 87%

Growth and patterning in the conodont skeleton

Donoghue

1998

Phil. Trans. R. Soc. Lond. B

108

146

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Recent advances in our understanding of conodont palaeobiology and functional morphology have rendered established hypotheses of element growth untenable. In order to address this problem, hard tissue histology is reviewed paying particular attention to the relationships during growth of the component hard tissues comprising conodont elements, and ignoring a priori assumptions of the homologies of these tissues. Conodont element growth is considered further in terms of the pattern of formation, of which four distinct types are described, all possibly derived from a primitive condition after heterochronic changes in the timing of various developmental stages. It is hoped that this may provide further means of unravelling conodont phylogeny. The manner in which the tissues grew is considered homologous with other vertebrate hard tissues, and the elements appear to have grown in a way similar to the growing scales and growing dentition of other vertebrates.

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“…The same factor would then be responsible for the supply of food and stimulation of mitosis and cell fission. In fact, such a network develops above the ganoine epithelium in the Recent fish Lepisosteus (Sire, 1994). The development of a lacuna preceded, according to this model, the origination of denticles.…”

Section: Fossil Evidence On the Origin Of Chordate The Dermal Skeletonmentioning

confidence: 91%

Hypotheses on the origin and early evolution of chordates in the light of recent zoological and palaeontological evidence

Simonetta¹,

Pucci²,

Dzik³

1999

Italian Journal of Zoology

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Both new palaeontological and embryological evidence on chordates require a reassessment of traditional ideas on their early phylogeny and on the evolution of their Bauplan and tissues. A revision of the available data from both palaeontological and zoological points of view is useful both to clarify the better justified possible hypotheses and to point to the more profitable lines of investigation for further advancing our understanding of these problems. Recent advances in the knowledge of the morphology of Cambrian protochordates and of conodonts provide significant evidence for the understanding of the earliest phases of development of typical vertebrate morphology. It appears that, in the oldest lineages related with the evolution of vertebrates, mineralized tissues may have been restricted to the bucco-pharyngeal region and be of ectodermal and ectomesenchymal origin. The development of dermal and visceral skeletal structures in living vertebrates further supports the overall significance of ectodermal-ectomesenchymal interactions as the first step towards the origin of the vertebrate skeleton.

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Light and TEM study of nonregenerated and experimentally regenerated scales of Lepisosteus oculatus (holostei) with particular attention to ganoine formation

Abstract: The processes of ganoine formation are similar to those known for the ganoine in the polypterid scales and to those described for enamel deposition in teeth. Ganoine is enamel.

Cited by 60 publications

References 22 publications

SMAD4-mediated WNT signaling controls the fate of cranial neural crest cells during tooth morphogenesis

SMAD4-mediated WNT signaling controls the fate of cranial neural crest cells during tooth morphogenesis

Growth and patterning in the conodont skeleton

Hypotheses on the origin and early evolution of chordates in the light of recent zoological and palaeontological evidence

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