A comparison of the larval and juvenile dentition in <i>Polypterus senegalus</i>

Clercq, Adelbert De; Vandenplas, Sam; Huysseune, Ann

doi:10.1111/jai.12531

Cited by 4 publications

(3 citation statements)

References 24 publications

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“…Still, replacement teeth develop from the outer dental epithelium of the predecessor tooth (Huysseune et al., ; Huysseune and Witten, ). The same situation is observed in the basal bony fish Polypterus senegalus (De Clercq et al., , in this volume). Such an intimate connection between predecessor and replacement tooth could well explain the arrangement of oral denticles in placoderms.…”

Section: The Many Shapes Of the Dental Laminasupporting

confidence: 78%

Old, new and new-old concepts about the evolution of teeth

2014

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The evolutionary origin of teeth from dermal denticles (odontodes) that developed in the mouth cavity, designated as outside-in hypothesis, has long been undisputed. The outside-in hypothesis is based on the conclusion that dermal denticles and teeth fulfil the criteria of homology in an exemplary manner. Over the past 15 years, this hypothesis has been challenged. Proponents of the alternative inside-out hypothesis suggest that teeth did not evolve from dermal denticles, that they are of endodermal origin (forming in conjunction with neural crest-derived mesenchyme) and that they evolved several times independently in different lineages of vertebrates. Key arguments for the inside-out hypothesis are mineralized structures of conodonts that are accepted as teeth, the exclusive acceptance of placoderm pharyngeal denticles as teeth, together with the rejection of the presence of teeth in basal placoderms. We summarize the results of recent studies that have been triggered by the fruitful discussion between the two conflicting hypotheses. New findings support the traditional outside-in hypothesis: the mineralized elements of conodonts are not teeth, and the oral cusps in basal placoderms are true teeth. Furthermore, new developmental and molecular data clarify homology between teeth and dermal denticles. Today a new synthesis is emerging about the evolutionary origin of teeth from dermal denticles and about the unity of the elements of the dermal skeleton

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Section: The Many Shapes Of the Dental Laminasupporting

confidence: 78%

Old, new and new-old concepts about the evolution of teeth

2014

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“…(d)]. Strongly mineralized skeletal matrix stains less with Alizarin red compared less mineralized matrix (Vandervennet et al , ; De Clercq et al , ). Higher magnification shows the same pattern in regular, fully mineralized, scales from animals of the P‐sufficient group (modest red, bright red and unstained) albeit condensed at the edge of the scale [Fig.…”

Section: Resultsmentioning

confidence: 99%

A primary phosphorus‐deficient skeletal phenotype in juvenile Atlantic salmon Salmo salar: the uncoupling of bone formation and mineralization

Witten

Owen

Fontanillas

et al. 2015

Journal of Fish Biology

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To understand the effect of low dietary phosphorus (P) intake on the vertebral column of Atlantic salmon Salmo salar, a primary P deficiency was induced in post‐smolts. The dietary P provision was reduced by 50% for a period of 10 weeks under controlled conditions. The animal's skeleton was subsequently analysed by radiology, histological examination, histochemical detection of minerals in bones and scales and chemical mineral analysis. This is the first account of how a primary P deficiency affects the skeleton in S. salar at the cellular and at the micro‐anatomical level. Animals that received the P‐deficient diet displayed known signs of P deficiency including reduced growth and soft, pliable opercula. Bone and scale mineral content decreased by c. 50%. On radiographs, vertebral bodies appear small, undersized and with enlarged intervertebral spaces. Contrary to the X‐ray‐based diagnosis, the histological examination revealed that vertebral bodies had a regular size and regular internal bone structures; intervertebral spaces were not enlarged. Bone matrix formation was continuous and uninterrupted, albeit without traces of mineralization. Likewise, scale growth continues with regular annuli formation, but new scale matrix remains without minerals. The 10 week long experiment generated a homogeneous osteomalacia of vertebral bodies without apparent induction of skeletal malformations. The experiment shows that bone formation and bone mineralization are, to a large degree, independent processes in the fish examined. Therefore, a deficit in mineralization must not be the only cause of the alterations of the vertebral bone structure observed in farmed S. salar. It is discussed how the observed uncoupling of bone formation and mineralization helps to better diagnose, understand and prevent P deficiency‐related malformations in farmed S. salar.

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“…It is also crucial to know how deformities that occur in wild fish differ from deformities of farmed fish (Sambraus et al., ). To obtain insights into common developmental processes, the study of basal bony fish species is important (De Clercq et al., ; Leprévost and Sire, ). There is substantial progress in understanding teleost skeletal metabolism documented in the fifth section ‘Nutrition and Metabolism’.…”

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confidence: 99%