Caenotropus labyrinthicus (Kner)

Scharcansky, Alexandre & Lucena, Carlos Alberto S., 2008, Phylogenetic assessment of ultrastructural and histological characters of teeth in the Anostomoidea, Hemiodontidae and Parodontidae (Teleostei: Ostariophysi: Characiformes), Zootaxa 1948 (1), pp. 36-56 : 40

Caenotropus labyrinthicus (Kner) ( Figs. 6 and 7 )

As the members of this family lack dentary teeth, the information below refers to premaxillary teeth.

The premaxillary teeth do not show nearby bone tissue. The bone tissue located far from the teeth is compact, without alveoli. The replacement teeth are in a region composed of connective tissue; they are arranged in a single row, and each one is aligned with and located immediately behind each functional teeth and do not show a pre-eruptive rotation. Posterior to the row of functional teeth, there is a conspicuous area of adipose tissue. All replacement teeth have a shape similar to that of the functional teeth. Histologically, replacement teeth in their final stage show a pattern similar to that of functional teeth from the exterior inwards: a thick enamel layer (light area of tooth, see Figure 7C ), which because it was totally mineralized was decalcified during histological preparation, surrounded by elongated ameloblasts. Next is the dentin layer. Starting from the enamel layer, we see conspicuous periodontal ligaments already fully developed. Finally, there is a small dental papilla consisting of mesenchymal cells.

The functional teeth are connected along the dentin layer to the connective tissue by small periodontal ligaments. The dentin layer is narrow on the tooth sides and thicker in the apical region. The dental pulp located in the tooth basal area is somewhat wider than in the meso-apical region, becoming narrower as it moves inside the connective tissue and apparently bordered in the back by the enamel layer.

Figures

FIGURE 6. Caenotropus labyrinthicus (Kner, 1858) MCP 22515, 59.35 mm SL - A: Premaxilla and teeth, frontal view. MCP 22515, 54.22 mm SL - B: Premaxilla and teeth, left side, internal view, median region. C: Tooth, premaxilla, left side, internal view, apical region. D: Premaxilla tooth, left side, SEM image showing the crystal apatite arrangement, labiolingual direction. E: Caenotropus schizodon Scharcansky & Lucena, 2007 MCP 30101, 81.84 mm SL, bilobate teeth, premaxilla, left side.

FIGURE 7. Caenotropus labyrinthicus (Kner, 1858) MCP 22515, 54.28 mm SL – A: Premaxilla, cross section (10x). Small arrow points the connective tissue surrounding each tooth. B: Replacement row teeth (20x). Small arrows points to the apical region of the replacement teeth. C: Replacement tooth (40x); D: Contact region of the functional teeth (20x). E: Premaxilla, cross section, functional teeth, showing that most of the tooth is embedded in epithelial tissue. AM=ameloblasts; DF=functional teeth; DN=dentin; DS=replacement teeth; ES=enamel; LP=periodontal ligament; OD=odontoblasts; PA= dental papilla; PO=pulp; PMX=premaxilla; TA=adipose tissue; TC=connective tissue; TE=epithelial tissue; TO=bone tissue.