Three-dimensional reconstruction studies and morphometric analysis of rudimental tooth primordia in the upper incisor region of the sheep (Ovis aries, Ruminantia)

Witter, Kirsti; Matulová, Petra; Mı́šek, Ivan

doi:10.1016/s0003-9969(02)00163-2

Cited by 5 publications

(2 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, it is widely known that ruminant artiodactyls possess a horny dental pad ( pulvinus dentalis ) composed of keratinous epithelium in lieu of upper incisors (Nickel et al, ; Hofmann et al, ; Schaller and Constantinescu, ; Pérez et al, ; Eurell and Frappier, ), yet the cheek teeth and lower incisors are well developed. Dental laminae and tooth primordia begin to develop in embryonic Ovis aries (Mayo, ; Witter and Míšek, ), although the tissues do not differentiate into tooth mesenchyme (Witter et al, ). The earliest ruminants retained the upper incisors from their earlier artiodactyl ancestors (Webb and Taylor, ), although those teeth were lost quickly in later diverging taxa (Janis and Scott, ).…”

Section: Discussionmentioning

confidence: 99%

Vascularization of the Gray Whale Palate (Cetacea, Mysticeti, Eschrichtius robustus): Soft Tissue Evidence for an Alveolar Source of Blood to Baleen

Ekdale

Deméré

Berta

2015

The Anatomical Record

View full text Add to dashboard Cite

The origin of baleen in mysticetes heralded a major transition during cetacean evolution. Extant mysticetes are edentulous in adulthood, but rudimentary teeth develop in utero within open maxillary and mandibular alveolar grooves. The teeth are resorbed prenatally and the alveolar grooves close as baleen germ develops. Arteries supplying blood to highly vascularized epithelial tissue from which baleen develops pass through lateral nutrient foramina in the area of the embryonic alveolar grooves and rudimentary teeth. Those vessels are hypothesized to be branches of the superior alveolar artery, but branches of the greater palatine arteries may play a role in the baleen vascularization. Through a combination of latex injection, CT, and traditional dissection of the palate of a neonatal gray whale (Eschrichtius robustus), we confirm that the baleen receives blood from vessels within the superior alveolar canal via the lateral foramina. The greater palatine artery is restricted to its own passage with no connections to the baleen. This study has implications for the presence of baleen in extinct taxa by identifying the vessels and bony canals that supply blood to the epithelium from which baleen develops. The results indicate that the lateral foramina in edentulous mysticete fossils are bony correlates for the presence of baleen, and the results can be used to help identify bony canals and foramina that have been used to reconstruct baleen in extinct mysticetes that retained teeth in adulthood. Further comparisons are made with mammals that also possess oral keratin structures, including ruminants, ornithorhynchid monotremes, and sirenians. Anat Rec, 298:691-702, 2015. V C 2015 Wiley Periodicals, Inc.Key words: baleen; gray whale; Eschrichtius robustus; vascularization; palateIn this article, we investigate the blood supply to the baleen and surrounding epithelium covering the hard palate in a neonatal gray whale (Eschrichtius robustus). Baleen is a neomorphic keratinous structure that is unique to mysticete cetaceans (baleen whales) and functions as a natural sieve to trap prey during filter feeding (Pivorunas, 1979;Werth, 2001Werth, , 2004Werth, , 2013. Baleen develops as a series of transverse laminae (main and minor plates) that form a pair of bilateral racks along the ventrolateral borders of the maxillae. The racks of baleen laminae (or baleen racks) are oriented parasagittally, and they are deeply embedded within the highly Additional Supporting Information may be found in the online version of this article.

show abstract

Section: Discussionmentioning

confidence: 99%

Vascularization of the Gray Whale Palate (Cetacea, Mysticeti, Eschrichtius robustus): Soft Tissue Evidence for an Alveolar Source of Blood to Baleen

Ekdale

Deméré

Berta

2015

The Anatomical Record

View full text Add to dashboard Cite

show abstract

“…Beside the ''hard'' vestigial teeth, vestigial tooth primordia that do not develop beyond the cap stage have been found in many species: e.g., in some marsupials, seals and sheeps (Moss-Saletijn, '78). Recently, embryonic tooth vestiges have been documented in Suncus murinus (Sasaki et al, 2001) and in the prospective toothless premaxilla of sheep (Witter et al, 2003).…”

Section: Atavistic and Vestigial Teeth In Mammalsmentioning

confidence: 99%

Phylogenetic memory of developing mammalian dentition

2006

View full text Add to dashboard Cite

Structures suppressed during evolution can be retraced due to atavisms and vestiges. Atavism is an exceptional emergence of an ancestral form in a living individual. In contrast, ancestral vestige regularly occurs in all members of an actual species. We surveyed data about the vestigial and atavistic teeth in mammals, updated them by recent findings in mouse and human embryos, and discussed their ontogenetic and evolutionary implications. In the mouse incisor and diastema regions, dental placodes are transiently distinct being morphologically similar to the early tooth primordia in reptiles. Two large vestigial buds emerge in front of the prospective first molar and presumably correspond to the premolars eliminated during mouse evolution. The incorporation of the posterior premolar vestige into the lower first molar illustrates the putative mechanism of evolutionary disappearance of the last premolar in the mice. In mutant mice, devious development of the ancestral tooth primordia might lead to their revivification and origin of atavistic supernumerary teeth. Similarity in the developmental schedule between three molars in mice and the respective third and fourth deciduous premolar and the first molar in humans raises a question about putative homology of these teeth. The complex patterning of the vestibular and dental epithelium in human embryos is reminiscent of the pattern of "Zahnreihen" in lower vertebrates. A hypothesis was presented about the developmental relationship between the structures at the external aspect of the dentition in mammals (oral vestibule, pre-lacteal teeth, paramolar cusps/teeth), the tooth glands in reptiles, and the earliest teeth in lower vertebrates.

show abstract