Fine structural and cytochemical observations of dental epithelial cells during the enameloid formation stages in red stingrays <i>Dasyatis akajei</i>

Sasagawa, Ichiro

doi:10.1002/jmor.1097

Cited by 11 publications

(5 citation statements)

References 16 publications

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“…Ameloblasts are also certainly involved in the degradation of the enameloid matrix by means of the synthesis of MMP20 (a collagenase). Until recently, the ameloblast contribution to enameloid formation and maturation was not demonstrated, and these conclusions were supported by various ultrastructural and immunohistochemical studies performed in chondrichthyans, teleosts and caudate amphibians (Goto, 1978;Prostak & Skobe, 1986Herold et al 1989;Sasagawa, 1989Sasagawa, , 2002Davit-Béal et al 2007). However, using in situ hybridization the expression of type 1 collagen by the ameloblasts during enameloid formation has been demonstrated unequivocally in a teleost (Huysseune et al 2008) and in a caudate larva (Sire et al unpubl.…”

Section: Hypermineralized (Capping) Tissuesmentioning

confidence: 95%

“…Until recently, the ameloblast contribution to enameloid formation and maturation was not demonstrated, and these conclusions were supported by various ultrastructural and immunohistochemical studies performed in chondrichthyans, teleosts and caudate amphibians (Goto, 1978; Prostak & Skobe, 1986, 1988; Herold et al. 1989; Sasagawa, 1989, 2002; Davit‐Béal et al. 2007).…”

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confidence: 98%

“…In living vertebrates, enameloid is present in chondrichthyans, actinopterygians (ray‐finned fish) and larval stages of caudate amphibians. Enameloid in these lineages is most likely homologous (Gillis & Donoghue, 2007) and not the product of convergent evolution (Sasagawa, 2002). Of particular importance to understanding the transition between these two hard tissues is the study of enameloid formation in the tetrapod lineage Caudata (= Urodela).…”

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confidence: 99%

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Origin and evolution of the integumentary skeleton in non‐tetrapod vertebrates

2009

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Most non-tetrapod vertebrates develop mineralized extra-oral elements within the integument. Known collectively as the integumentary skeleton, these elements represent the structurally diverse skin-bound contribution to the dermal skeleton. In this review we begin by summarizing what is known about the histological diversity of the four main groups of integumentary skeletal tissues: hypermineralized (capping) tissues; dentine; plywood-like tissues; and bone. For most modern taxa, the integumentary skeleton has undergone widespread reduction and modification often rendering the homology and relationships of these elements confused and uncertain. Fundamentally, however, all integumentary skeletal elements are derived (alone or in combination) from only two types of cell condensations: odontogenic and osteogenic condensations. We review the origin and diversification of the integumentary skeleton in aquatic non-tetrapods (including stem gnathostomes), focusing on tissues derived from odontogenic (hypermineralized tissues, dentines and elasmodine) and osteogenic (bone tissues) cell condensations. The novelty of our new scenario of integumentary skeletal evolution resides in the demonstration that elasmodine, the main component of elasmoid scales, is odontogenic in origin. Based on available data we propose that elasmodine is a form of lamellar dentine. Given its widespread distribution in non-tetrapod lineages we further propose that elasmodine is a very ancient tissue in vertebrates and predict that it will be found in ancestral rhombic scales and cosmoid scales.

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Section: Hypermineralized (Capping) Tissuesmentioning

confidence: 95%

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confidence: 98%

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confidence: 99%

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Origin and evolution of the integumentary skeleton in non‐tetrapod vertebrates

2009

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“…During the early stage of enameloid maturation, the thick lamina densa that has been situated beneath the IDE cells disap- peared and large numbers of vesicles as well as occasionally invaginations of the distal cell membrane were found at their distal end (Figs. 19, 20;Sasagawa, 1999Sasagawa, , 2002Sasagawa and Akai, 1999). During the enameloid mineralization and maturation stages, tall IDE cells contained well-developed Golgi apparati, numerous mitochondria, cisternae of RER and smooth endoplasmic reticulum (SER), electron-dense granules, and vesicles.…”

Section: Dental Epithelial Cells Are Probably Involved Inmentioning

confidence: 98%

“…These findings suggest that the IDE cells are probably involved in material transport from/to the enameloid and calcium transport. Consequently, it is likely that the dental epithelial cells are involved in the removal of organic matrix from the enameloid and in the process of crystal growth during the later stages of enameloid formation, i.e., the stages of enameloid mineralization and maturation (Sasagawa, 1999(Sasagawa, , 2002Sasagawa and Akai, 1999).…”

Section: Dental Epithelial Cells Are Probably Involved Inmentioning

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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Mineralization of Basement Membrane Mediates Dentogingival Adhesion in Mammalian and Nonmammalian Vertebrates

Sawada

Inoué

2003

Calcified Tissue International

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In order to elucidate the mechanism of adhesion between the gingiva and the tooth, detailed comparative ultrastructural studies of the dentogingival border were done in the monkey and shark. The tissues were prepared with or without demineralization for the ultrastructural observations. At the border, the internal basement membrane, which is firmly bound to the junctional epithelium through hemidesmosomes, was specialized differently in these species. In the monkey, the lamina densa was closely associated at its enamel side with an additional layer which had characteristics of the lamina densa and was referred to as the supplementary lamina densa. In the shark, the lamina densa showed a unique, hemidesmosome-related specialization in the form of the intermittent occurrence of bulges along its surface facing the epithelium. In nondemineralized tissues a part of the basement membrane, that is, the supplementary lamina densa (monkey) and the main lamina densa but not bulges (shark), was preferentially mineralized. The mineral deposit was continuous with that in the enamel and enameloid/dentine, thus constituting an advancing edge of mineralization. The network arrangement of the mineral crystals in the monkey basement membrane resembled the pattern of the cord network of the basement membrane, suggesting the presence of a delicate mutual basement membrane-mineral interaction. Thus, the organic phase and the mineral phase are allowed to make contact at this mineralized area of the basement membrane and firmly bind to one another. Therefore, strong gingiva-tooth adhesion is established by partial mineralization of the internal basement membrane, in a way similar to that found in the previously reported association of maturation stage ameloblasts with the enamel.

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Fine structural and cytochemical observations of dental epithelial cells during the enameloid formation stages in red stingrays Dasyatis akajei

Cited by 11 publications

References 16 publications

Origin and evolution of the integumentary skeleton in non‐tetrapod vertebrates

Origin and evolution of the integumentary skeleton in non‐tetrapod vertebrates

Mineralization patterns in elasmobranch fish

Mineralization of Basement Membrane Mediates Dentogingival Adhesion in Mammalian and Nonmammalian Vertebrates

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