Morphological changes in the oral (Buccopharyngeal) membrane in urodelan embryos: Development of the mouth opening

Takahama, Hideki; Sasaki, Fumio; Watanabe, Kyozo

doi:10.1002/jmor.1051950106

Cited by 10 publications

(9 citation statements)

References 12 publications

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“…Anatomical characterization in diverse systems including sea urchins, urodeles, Xenopus , and mouse have suggested that interactions between foregut and stomodeal ectoderm are important for oral perforation (Dickinson and Sive, 2006; Hardin and Armstrong, 1997; McClay et al, 1992; Poelmann et al, 1985; Soukup et al, 2013; Takahama et al, 1988; Theiler, 1969; Watanabe et al, 1984; Waterman, 1977). However, molecular regulation of primary mouth opening is largely untested, especially as perforation occurs early in development and perturbation of major signaling cascades results in broad cranial defects.…”

Section: Resultsmentioning

confidence: 99%

“…The primary mouth marks the location of this interface, and perforation is essential (Dickinson and Sive, 2006; Hardin and Armstrong, 1997; McClay et al, 1992; Poelmann et al, 1985; Soukup et al, 2013; Takahama et al, 1988; Watanabe et al, 1984). Despite the fundamental importance of the primary mouth, little is known about the molecular control of its development.…”

Section: Introductionmentioning

confidence: 99%

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Hedgehog activity controls opening of the primary mouth

Tabler

Bolger

Wallingford

et al. 2014

Developmental Biology

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To feed or breathe, the oral opening must connect with the gut. The foregut and oral tissues converge at the primary mouth, forming the buccopharyngeal membrane (BPM), a bilayer epithelium. Failure to form the opening between gut and mouth has significant ramifications, and many craniofacial disorders have been associated with defects in this process. Oral perforation is characterized by dissolution of the BPM, but little is known about this process. In humans, failure to form a continuous mouth opening is associated with mutations in Hedgehog (Hh) pathway members; however, the role of Hh in primary mouth development is untested. Here, we show, using Xenopus, that Hh signaling is necessary and sufficient to initiate mouth formation, and that Hh activation is required in a dose-dependent fashion to determine the size of the mouth. This activity lies upstream of the previously demonstrated role for Wnt signal inhibition in oral perforation. We then turn to mouse mutants to establish that SHH and Gli3 are indeed necessary for mammalian mouth development. Our data suggest that Hh-mediated BPM persistence may underlie oral defects in human craniofacial syndromes.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hedgehog activity controls opening of the primary mouth

Tabler

Bolger

Wallingford

et al. 2014

Developmental Biology

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“…Bichir mouth development, however, resembles the developmental mode known from urodele amphibians (e.g. Johnston, 1910; Adams, 1924; de Beer, 1947; Takahama et al., 1988). In the Mexican axolotl, for example, the oral ectoderm does not invaginate, but instead, only the basal layer of the oral ectoderm moves inwards to cover the surface of the mouth endoderm as the so called stomodeal collar.…”

Section: Resultsmentioning

confidence: 99%

Mouth development in the Senegal bichirPolypterus senegalusdoes not involve the oropharyngeal membrane: possible implications for the ecto-endoderm boundary and tooth initiation

Kralovič

Horáček

Cerny

2010

Journal of Applied Ichthyology

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Summary Polypterid fishes are considered the basal‐most group of extant actinopterygians and thus may serve as a direct link to understand the evolution of the first bony fishes. Embryonic and larval specimens, however, are extremely scarce, making it difficult to study their developmental patterns and processes. During the past few years we collected many embryos and larvae of the Senegal bichir Polypterus senegalus and in this paper we describe some novel observations concerning the supposed ecto‐endoderm border in the mouth and consecutive initiation of dental development. The mouth of the Senegal bichir does not develop via a classical oropharyngeal membrane but instead, opening the mouth occurs via a separation of the upper and lower jaws that are connected by epithelial bridges. These structures are bilaterally symmetrical and are found invariantly at places of the earliest tooth bud development. It is suggested that the epithelial bridges may represent the ecto‐endoderm bordering zone, are both structurally and functionally homologous to the oropharyngeal membrane and consequently it is hypothesized that the epithelial bridges and the developmental factors producing them play a key role in initiation and early distribution of the particular dental domains.

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“…3A). The stomodeum with a well‐defined lumen does not develop, and only a shallow groove is visible externally (Takahama et al. 1988).…”

Section: Modes Of Primary Mouth Formation In Vertebratesmentioning

confidence: 99%

Development and evolution of the vertebrate primary mouth

2012

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The vertebrate oral region represents a key interface between outer and inner environments, and its structural and functional design is among the limiting factors for survival of its owners. Both formation of the respective oral opening (primary mouth) and establishment of the food-processing apparatus (secondary mouth) require interplay between several embryonic tissues and complex embryonic rearrangements. Although many aspects of the secondary mouth formation, including development of the jaws, teeth or taste buds, are known in considerable detail, general knowledge about primary mouth formation is regrettably low. In this paper, primary mouth formation is reviewed from a comparative point of view in order to reveal its underestimated morphogenetic diversity among, and also within, particular vertebrate clades. In general, three main developmental modes were identified. The most common is characterized by primary mouth formation via a deeply invaginated ectodermal stomodeum and subsequent rupture of the bilaminar oral membrane. However, in salamander, lungfish and also in some frog species, the mouth develops alternatively via stomodeal collar formation contributed both by the ecto-and endoderm. In ray-finned fishes, on the other hand, the mouth forms via an ectoderm wedge and later horizontal detachment of the initially compressed oral epithelia with probably a mixed germ-layer derivation. A very intriguing situation can be seen in agnathan fishes: whereas lampreys develop their primary mouth in a manner similar to the most common gnathostome pattern, hagfishes seem to undergo a unique oropharyngeal morphogenesis when compared with other vertebrates. In discussing the early formative embryonic correlates of primary mouth formation likely to be responsible for evolutionary-developmental modifications of this area, we stress an essential role of four factors: first, positioning and amount of yolk tissue; closely related to, second, endoderm formation during gastrulation, which initiates the process and constrains possible evolutionary changes within this area; third, incipient structure of the stomodeal primordium at the anterior neural plate border, where the ectoderm component of the prospective primary mouth is formed; and fourth, the prime role of Pitx genes for establishment and later morphogenesis of oral region both in vertebrates and non-vertebrate chordates.

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Morphological changes in the oral (Buccopharyngeal) membrane in urodelan embryos: Development of the mouth opening

Cited by 10 publications

References 12 publications

Hedgehog activity controls opening of the primary mouth

Hedgehog activity controls opening of the primary mouth

Mouth development in the Senegal bichirPolypterus senegalusdoes not involve the oropharyngeal membrane: possible implications for the ecto-endoderm boundary and tooth initiation

Development and evolution of the vertebrate primary mouth

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