Structure of comblike teeth of the ayu sweetfish, Plecoglossus altivelis (Teleostei: Isospondyli): I. Denticles and tooth attachment

Abstract

The structure and tooth attachment of the comblike teeth and denticles of the ayu sweetfish, Plecoglossus altivelis, were examined by light and scanning electron microscopy. The denticle is composed of a spoonlike crown with a spine pointed anteriorly, a triangular plate in the cervical region, and a root that curves laterally and tapers off to a point. The root apex is fused with a long thin pedicle that turns abruptly anteriad toward the jaw bone. Planes of the spine, the spoonlike crown, the triangle plate and the root of the denticle are varied, and the denticle is twisted in the region of the triangle plane. The superficial layer of the dentine is homogeneously calcified and is considered to be enameloid, because some of the inner dentinal epithelial cells in the tooth germ are columnar and possess cellular processes at their apical ends. The dentine is fibrous and fine dentinal tubules are visible in dentine treated with sodium hydroxide and observed by scanning electron microscopy. The upper half of the root is surrounded by a dense layer of collagen fibers running parallel to the tooth axis, and the lower half is encompassed by interlaced collagen fibers. The lower part of the root is open on its lingual side. The pedicle is a long rod which is homogeneously calcified and enmeshed by interlaced collagen fibers, and it curves mediad as it nears the jaw bone. The pedicles are interposed between a layer of gelatinous connective tissue and the jaw bone and terminate on the periosteum. Comparative aspects of ayu tooth morphology are discussed. © 1993 Wiley-Liss, Inc.

Morphology and development of teeth and epidermal brushes in loricariid catfishes

“…In all these cases the diet primarily consists of adherent algae. Examples in teleosts are the rake-like denticles of the osmeriform ayu (Howes and Sanford, 1987;Uehara and Miyoshi, 1993), the tooth-like keratinous hooks of Gyrinocheilidae (Ono, 1980;Benjamin, 1986), spatulate teeth of certain Cichlidae (Vandervennet et al, 2006) and Mochokidae, and the scraping teeth of species of the Loricariidae or suckermouth armored catfishes. The latter family exhibits the most exquisite and diverse teeth forms (e.g., Muller and Weber, 1992;Schaefer and Stewart, 1993;Delariva and Agostinho, 2001): the S-or Z-shaped recurved teeth are generally asymmetrically bicuspid, but, in some taxa, have one cusp only.…”