Beiträge zur Entwicklungsgeschichte von Zähnen und Gebiss der Reptilien

Woerdeman, M. W.

doi:10.1007/bf02978970

Cited by 38 publications

(12 citation statements)

References 3 publications

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“…So far, the economy of speculation required to construct the Tooth Family theory (merely a sphere of inhibition temporarily surrounding each developing tooth) far surpasses the number and complexity of biologically improbable speculations required by the Zahnreihe theory; and both theories can account for the ontogeny of the wave replacement of alternate teeth. Unfortunately, neither theory accounts for any description yet given of the sequence of tooth initiation in embryo reptiles (Harrison, 1901;Woerdeman, 1919: Osborn, 1971) and mammals (Osborn, 1970). Woerdeman (1919) gave a somewhat prolix account of the ontogeny of the crocodilian dentition.…”

Section: The Modelmentioning

confidence: 99%

“…Unfortunately, neither theory accounts for any description yet given of the sequence of tooth initiation in embryo reptiles (Harrison, 1901;Woerdeman, 1919: Osborn, 1971) and mammals (Osborn, 1970). Woerdeman (1919) gave a somewhat prolix account of the ontogeny of the crocodilian dentition. Because he failed to reconstruct these developing dentitions his descriptions may be inaccurate.…”

Section: The Modelmentioning

confidence: 99%

“…It was evident that the Zahnreihe theory could not account for dental ontogeny in this animal. He also pointed out that neither of the other two longitudinal studies of the sequence of tooth development in embryo reptiles (Harrison, 1901: Woerdeman, 1919 supported the theory. In the same paper Osborn (1971) formulated a theory based on biological controls within tooth families (a tooth family consists of the teeth which sequentially occupy a tooth position) rather than Zahnheihen (tooth rows which extend from the front to the back of the jaw).…”

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confidence: 98%

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On the Biological Improbability of Zahnreihen as Embryological Units

Osborn

1972

Evolution

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Section: The Modelmentioning

confidence: 99%

Section: The Modelmentioning

confidence: 99%

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confidence: 98%

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On the Biological Improbability of Zahnreihen as Embryological Units

Osborn

1972

Evolution

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“…Snakes and lizards, for example, generally form multiple sets of teeth throughout life (polyphyodonty), whereas mammals form only two. Despite being a topic of study for over a century (Bolk, 1922;Edmund, 1960;Leche, 1895;Woerdeman, 1919), the cellular basis of tooth replacement is poorly understood. Two reasons account for this.…”

Section: Introductionmentioning

confidence: 99%

Identification of putative dental epithelial stem cells in a lizard with life-long tooth replacement

2010

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SUMMARYMost dentate vertebrates, including humans, replace their teeth and yet the process is poorly understood. Here, we investigate whether dental epithelial stem cells exist in a polyphyodont species, the leopard gecko (Eublepharis macularius). Since the gecko dental epithelium lacks a histologically distinct site for stem cells analogous to the mammalian hair follicle bulge, we performed a pulse-chase experiment on juvenile geckos to identify label-retaining cells (LRCs). We detected LRCs exclusively on the lingual side of the dental lamina, which exhibits low proliferation rates and is not involved in tooth morphogenesis. Lingual LRCs were organized into pockets of high density close to the successional lamina. A subset of the LRCs expresses Lgr5 and other genes that are markers of adult stem cells in mammals. Also similar to mammalian stem cells, the LRCs appear to proliferate in response to gain of function of the canonical Wnt pathway. We suggest that the LRCs in the lingual dental lamina represent a population of stem cells, the immediate descendents of which form the successional lamina and, ultimately, the replacement teeth in the gecko. Furthermore, their location on the non-tooth-forming side of the dental lamina implies that dental stem cells are sequestered from signals that might otherwise induce them to differentiate.

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“…Edmund has produced the theoretical basis for understanding the patterns of tooth succession in the lower vertebrates and has shown that these patterns may be explained by a consideration of tooth production and tooth replacement. He accepts the term Zahnreihe of Woerdeman (1919Woerdeman ( , 1921 to describe the teeth which are produced by an initiating stimulus (as it moves caudad along the jaw) before the arrival of the next such stimulus. Gillette (1955) has shown that the life cycle of the tooth in Runa pipiens may be divided into a number of stages, either on strictly morphological grounds, or on the degree of morphological change which occurs during equal fractions of the relative time occupied by the total life cycle.…”

Section: Introductionmentioning

confidence: 99%

The development and replacement of teeth in Hypogeophis rostratus (Amphibia, Apoda)

Lawson

1965

Proceedings of the Zoological Society of London

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The details of tooth development in Hypogeophis rostratus are described and analysed by dividing the life cycle of the tooth into a number of stages. Such divisions are based on either morphological characters or the degree of change which occurs during equal fractions of the whole life cycle. On the basis of such data it is apparent that some phases of the development of the tooth take place slowly whilst others are passed through more rapidly. Such variations result in the production of a dentition in which each locus is generally occupied by a functional tooth and a replacement tooth at an earlier stage of development. The process of tooth development in general follows the pattern described in Salamandra maculosa by Kerr (1960), and the enamel which covers the major and minor cusps of the adult tooth is considered to be of ectodermal origin. A stage at which the enamel matrix occurs in an uncalcified stage has not been found in Hypogeophis rostratus and it is assumed that calcification of the enamel occurs almost simultaneously with the production of its organic matrix. The crown and the pedicel of the mature tooth are connected by a ring of fibres, and it seems likely that the asymmetrical pedicel is ankylosed to the jaw bone by a thin layer of cement. The mechanism of tooth succession is investigated and it is clear that both tooth production and tooth replacement occur in a synchronous manner. The term Zahnreihen (Woerdeman, 1919, 1921, and Edmund 1960, 1962) is accepted, and used in the description of tooth succession. It is clear that tooth production and replacement occur in much the same manner as in the reptiles (and possibly in all non‐mammalian vertebrates (Edmund, 1960)) and can be explained by the fact that the Zahnreihen are on average 2·4 tooth spaces apart and that each replacement wave (which travels craniad along the jaw) usually contains about six teeth. The results obtained in H. rostratus in no way conflict with the idea that the Zahnreihen are produced by stimuli which travel caudad along the jaw and that the replacement waves may run in the reverse direction. A theoretical template based on Zahnreihen 2·4 spaces apart is constructed and shows that replacement waves contain six teeth and run craniad along the jaw. It is pointed out that the observed facts do not exactly follow the theoretical pattern in that the distance between successive Zahnreihen may vary and that replacement rows may involve more or less than six teeth. Finally it is affirmed that such deviations are to be regarded as normal variations in the process of tooth production and replacement.

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Beiträge zur Entwicklungsgeschichte von Zähnen und Gebiss der Reptilien

Cited by 38 publications

References 3 publications

On the Biological Improbability of Zahnreihen as Embryological Units

On the Biological Improbability of Zahnreihen as Embryological Units

Identification of putative dental epithelial stem cells in a lizard with life-long tooth replacement

The development and replacement of teeth in Hypogeophis rostratus (Amphibia, Apoda)

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