Ultrastructure of the dental epithelium and odontoblasts during enameloid matrix deposition in cichlid teeth

Abstract

Teleost enameloid matrix has been proposed to be an ectodermal, mesodermal, or joint ectodermal-mesodermal product. To determine its origin we examined the ultrastructure of the inner dental epithelium (IDE), odontoblasts, enameloid, and dentin matrices of cichlid tooth buds at the stage of enameloid formation. © Alan R. Liss, Inc. Columnar IDE cells had apical and basal terminal webs and contained organelles associated with protein synthesis, including elongated secretory granules containing fibrillar material having cross-striations with 60-nm periodicity. The morphology of IDE secretory granules was typical of procollagen granules observed in a large variety of ectodermal and mesodermal cells synthesizing collagen. In contrast, the paucity of secretory granules within three odontoblast types indicates that these cells probably do not synthesize enameloid matrix. These observations are consistent with the idea that the bulk of the enameloid matrix is itself an ectodermal collagen synthesized and secreted by IDE cells.

Development and fine structure of pharyngeal replacement teeth in juvenile zebrafish ( Danio rerio) (Teleostei, Cyprinidae)

“…These findings are in accordance with literature reports on the ameloblasts in other teleosts (e.g. Shellis 1978;Prostak and Skobe 1986a;Sasagawa 1995;Huysseune and Sire 1997a) and in mammals (e.g. reviews in Deutsch et al 1995;Smith and Nanci 1995).…”

“…As in other teleosts, IDE and ODE remain in close apposition, without an intervening stratum intermedium or stellate reticulum (Kerr 1960;Bergot 1975;Prostak and Skobe 1986a;Sasagawa 1995). Sauvage (1972), however, has reported the presence of a stratum intermedium and of a reticulum stellatum in tooth germs of the goldfish Carassius auratus.…”

First‐generation teeth in nonmammalian lineages: Evidence for a conserved ancestral character?

“…The matrix vesicles are produced by budding off from odontoblast processes and they may play an important role in initiating mineralization at the junction between the enameloid and dentine, but not elsewhere (Sasagawa, 1988). Matrix vesicles have been reported in the small teeth of sparid larvae by Sasaki et al (1982) but Prostak and Skobe (1986a) did not find such vesicles in the forming enameloid in juvenile cichlids (although they were found in a cichlid by Sasagawa, 1988).…”

“…Teeth have an individual attachment to a bone support and are replaced individually (except in piranhas; see Roberts, 1975;Berkovitz, 1975Berkovitz and Shellis, 1978). Enameloid is deposited first by odontoblasts that synthesize dentine beneath the enameloid (Shellis and Miles, 1976;Sasagawa and Igarashi, 1985;Prostak and Skobe, 1986a;Sasagawa and Ferguson, 1990;Sasagawa, 1992). Histochemical and autoradiographic evidence suggests that the inner dental epithelium cells in teleosts and ameloblasts in tetrapods secrete similar matrix proteins (Shellis and Miles, 1974).…”

Ganoine Formation in the Scales of Primitive Actinopterygian Fishes, Lepisosteids and Polypterids

“…In decalcified samples, the process of maturation of the preganoine appears to result in the progressive disappearance of its organic matrix, which is removed along with the mineral (Figs. [22][23][24][25][26][27][28]. When decalcified in the first stages of maturation, the ganoine matrix looks less well organized in the basal region of the layer than in its upper region (Fig.…”