Chick tooth induction revisited

Abstract

Teeth have been missing from Aves for almost 100 million years. However, it is believed that the avian oral epithelium retains the molecular signaling required to induce odontogenesis, and this has been widely examined using heterospecific recombinations with mouse dental mesenchyme. It has also been argued that teeth can form from the avian oral epithelium owing to contamination of the mouse mesenchyme with mouse dental epithelial cells. To investigate the possibility of tooth formation from chick oral epithelium and the characteristics of possible chick enamel, we applied LacZ transgenic mice during heterospecific recombination and examined the further tooth formation. Transmission electron microscopy was used to identify the two tissues during development after heterospecific recombination. No mixing was detected between chick oral epithelium and mouse dental mesenchyme after 2 days, and secretory ameloblasts with Tomes' processes were observed after 1 week. Teeth were formed after 3 weeks with a single cusp pattern, possibly determined by epithelial factors, which is similar to that of the avian tooth in the late Jurassic period. These recombinant teeth were smaller than mouse molars, whereas perfect structures of both ameloblasts and enamel showed histological characteristics similar to those of mice. Together these observations consistent with previous report that odontogenesis is initially directed by species-specific mesenchymal signals interplaying with common epithelial signals.

From snout to beak: the loss of teeth in birds

“…Previous rough estimates have suggested that edentulism in Neornithes was reached within a narrow possible time interval, generally between 100 and 80 Ma [5,6,12,20]. By contrast, we notice that the available data allow a wider possible interval between circa 125 Ma and 65.5 Ma.…”

“…Therefore, the true teeth obtained through recent mouse mesenchyme-chicken epithelium recombinations [20] are likely to result from contamination by mouse epithelium, because chick epithelium is definitely unable to produce enamel. However, the shape of some teeth obtained by these authors surprisingly resembles Archaeopteryx or alligator teeth [20]. This might result from conserved dental morphogenetic determinants in the chick epithelium.…”

A comparative examination of odontogenic gene expression in both toothed and toothless amniotes

“…One inevitable question that arises is whether it is possible to induce tooth development, or to “turn teeth back on” in modern turtles. Researchers have partially rescued odontogenesis in chicks (Kollar and Fisher, ; Kollar and Mina, ; Chen et al, ; Mitsiadis et al, ; Mitsiadis et al, ; Cai et al, ), although the potential for enamelization may be small due to the loss of enamel‐specific genes from the chick genome (Sire et al, ). Tooth loss in turtles occurred in the Jurassic (201.6–145.5 Ma), much longer ago than tooth loss occurred in any mammals (Cenozoic) or in birds (Cretaceous).…”

Feedback control from the jaw joints during biting: An investigation of the reptile Sphenodon using multibody modelling

“…5), notably trigger fish (Soule, 1969), extinct mosasauroid lizards (Caldwell, 2007;Luan et al, 2009), at least one fossil snake (Budney et al, 2006), crocodiles (e.g., Tadokoro et al, 1998;McIntosh et al, 2002), and many extinct archosaurs including some dinosaurs and early birds (e.g, Edmund, 1960), argues for its general utility in the coordination of feeding activity. It is even found in modern birds that have been manipulated to redevelop teeth (Cai et al, 2009). However, investigations on mammals (particularly primates) have theorised that balancing side muscle activity must decrease to avoid disarticulation of the working side joint (Spencer, 1998;Greaves, 1982;Throckmorton et al, 1990;Koolstra and van Eijden, 1995).…”