Fig 1.
Oral jaw teeth in Anoplogaster cornuta.
(a) Right lateral view of head showing the three teeth on the premaxilla. (b) Right lateral view of the lower jaw showing the four teeth on the dentary. (c) Right first premaxillary tooth, lateral view. Note transparency of the dentin and pointed tooth tip. (d) Right third premaxillary tooth, lateral view. Note rounded tooth tip. (e) Left first dentary tooth, lateral view. Note pointed tooth tip. (f) Rounded, knob-like tip of right second dentary tooth, medial view. Due to the transparency of the dentin the extension of the pulp cavity is visible.
Fig 2.
Oral jaw teeth and supporting bone in Anoplogaster cornuta.
(a) Basal portion of right first premaxillary tooth, bone of attachment (asterisk) and premaxillary bone (P), medial view. The cleared and stained specimen shows intense staining of dentin and bone by alizarin red S. Insert: SEM-BSE image of the empty socket of the second premaxillary tooth, lateral view. (b) Transition zone between basal portion of left first dentary tooth and bone of attachment (asterisk). Arrowhead: Collar of mineralized collagen fibers. (c) SEM-BSE image of transition zone between basal portion of left second dentary tooth and bone of attachment (asterisk), lateral view. Note regular longitudinal corrugation of the tooth surface, collar of mineralized collagen fibers (arrowhead), and presence of numerous osteocyte lacunae (arrows) in the supporting dentary bone compared to lack of such lacunae in the bone of attachment. (d) Higher magnification of the transition zone between basal tooth portion and bone of attachment with collar of mineralized collagen fibers.
Fig 3.
Anterior portion of right premaxilla of Anoplogaster cornuta, cleared and stained (Alizarin red S, alcian blue 8 GX) specimen, medial view.
No replacement tooth is present at the empty locus (asterisk) of the second premaxillary tooth.
Fig 4.
Light micrographs of longitudinal ground sections of lower oral jaw teeth of Anoplogaster cornuta.
(a) Anterior wall of the shaft of the left first dentary tooth showing intense ramification of tubules in central dentin, and inner (juxtapulpal) dentinal zone (asterisk) with only few tubules. P: Pulp cavity. Arrow points to the tooth surface. A cleft between the tooth surface and the embedding resin (R) appears as a bright zone. Transmitted light with phase-contrast. (b) Shaft of left third dentary tooth showing extension and ramification of dentinal tubules, tooth tip to left of image. P: Pulp cavity. Normal transmitted light. (c) Tip of left third dentary tooth showing ramification of dentinal tubules in central dentin. Note lack of an enameloid cap. P: Pulp cavity. Arrow points to tooth surface. A cleft between tooth surface and embedding resin (R) appears as a bright zone. Transmitted light with phase-contrast. (d) Tip of left third dentary tooth showing that the dentinal tubules typically cannot be traced up to the tooth surface. Note lack of an enameloid cap. Arrows: Openings of dentinal tubules at the pulpal border. P: Pulp cavity. Normal transmitted light.
Fig 5.
(a) SEM-BSE image of polished longitudinal section of left first dentary tooth. Note uniform gray level (indicative of homogeneous mineralization) of the dentin and lack of an enameloid cap. (b) SEM-BSE image of the surface of a right third dentary tooth, lingual view. At the tooth tip, dentinal tubules have been exposed by wear (arrows). In a less worn area slightly more proximally, the dentinal tubules are occluded by a tissue (arrowheads) that appears brighter (i.e., more mineralized) than the surrounding dentin.
Fig 6.
Transverse section through the tip region of a right first dentary tooth of Anoplogaster cornuta.
(a) SEM-BSE image showing uniform gray level distribution (indicative of homogeneous mineralization) of the dentin. The position of the EDS line profile is indicated by the green line. P: Pulp cavity. (b) SEM-EDS line profile showing variation of calcium (Ca) and phosphorus (P) concentrations (relative values) across the dentinal wall. An enameloid layer with higher Ca and P concentrations is not present. Asterisk: Pulp cavity.
Fig 7.
Light micrographs of longitudinal ground sections showing basal portion of lower oral jaw teeth and bone of attachment in Anoplogaster cornuta.
(a) Left first dentary tooth. B: Bone of attachment; C: Collar of mineralized collagen fibers; D: Dentin; P: Pulp cavity. Posterior to top of image. Circularly polarized transmitted light. (b) Higher magnification of transition zone between basal anterior dentinal tooth shaft (D) and bone of attachment (B) of left first dentary tooth. C: Collar of mineralized collagen fibers. Circularly polarized transmitted light.
Fig 8.
SEM-BSE image of polished longitudinal section through basal portion of left first dentary tooth and adjacent bone of attachment.
Location of SEM-EDS point measurement spots is indicated by red crosses in the dentin (D) and blue crosses in the bone of attachment (B). Note lack of osteocyte lacunae in the bone of attachment. Arrow: Mineralized collagen fibers.
Table 1.
Calcium (Ca) and phosphorus (P) concentrations (normalized values) obtained by SEM-EDS for dentin and bone of attachment (eight measurement spots each, for location see Fig 7) of a left first dentary tooth of Anoplogaster cornuta and Ca/P ratios for the two tissues.
P-values (two-tailed) are from unpaired t-tests.
Fig 9.
Tooth fields in the dorsal and ventral oropharynx of Anoplogaster cornuta, cleared and stained (Alizarin red S, alcian blue 8 GX) specimen.
(a) In the roof of the oropharynx, paired tooth fields are located on the dermopalatines (1), the ectopterygoids (2) and the entopterygoids (3). Note that the teeth on the posterior tooth fields are larger than those on the dermopalatines. (b) In the floor of the oropharynx, paired tooth fields are present on the pharyngobranchials of the second (4) and third (5) branchial arches and on the ceratobranchials of the fifth branchial arch (6). (c) Higher magnification of tooth fields on the pharyngobranchials. Note presence of small teeth (arrows) diagnosed as replacement teeth and of empty tooth loci (one marked by arrowhead).
Fig 10.
Tooth fields in the dorsal oropharynx of Anoplogaster cornuta, cleared and stained (Alizarin red S, alcian blue 8 GX) specimen.
(a) Tooth field on the right ectopterygoid, note empty tooth locus (arrowhead). (b) Tooth field on the right entopterygoid. Note ring-like collagenous tissue (arrows in b) connecting the tooth base to the dentigerous bone.
Fig 11.
SEM-BSE images of tooth-bearing bones in the dorsal oropharynx of Anoplogaster cornuta, macerated specimen, anterior to left of images.
(a) Teeth from the right ectopterygoid. The small tooth is regarded as a recently established replacement tooth. (b) Detail of a tooth base on the right ectopterygoid. The tooth is slightly lowered into the underlying bone cavity. (c) Teeth on the left entopterygoid. Note empty tooth position (arrow) with ring-like collagenous attachment structure still in place. (d) Pharyngeal teeth on the right dermopalatine attached to a bony socket. Note narrow clefts (arrows) previously occupied by a collagenous attachment structure.
Fig 12.
SEM-BSE images of teeth and dentigerous bone (a, b) and bony projections (odontoids) (c) in the oropharynx of Anoplogaster cornuta. (a) Multiple cavities (asterisks) are present in the entopterygoid. (b) Broad connection between pulp cavity (P) and cavities in the dentigerous bone (B) (entopterygoid). Note collagenous connection (asterisk) between tooth base and bone. D: Dentin. (c) Bony projections (odontoids) emanating from a mesh-like bone in the roof of the oropharynx. Posterior to left of image.
Fig 13.
Teeth on the branchial arches of Anoplogaster cornuta.
(a) Single or multiple monocuspid teeth are attached to trabecular bony plates (asterisk) located on a branchial arch (BA). Arrow: Gill filament. Cleared and stained (Alizarin red S, alcian blue 8 GX) specimen. (b) Bony plate (asterisk) with single attached tooth and cup-like notch (+) on a branchial arch (BA) where a tooth-bearing bony plate has been lost. Unstained, macerated specimen. (c) and (d) SEM-BSE images of single (c) or multiple (d) monocuspid teeth attached to bony plates (asterisks) with trabecular architecture. Note ring-like seams at the attachment sites of the teeth on the bony plates. The bony plates are fixed by collagen fibers to the branchial arches (BA).