A polyphyodont is any animal whose teeth are continually replaced. In contrast, diphyodonts are characterized by having only two successive sets of teeth.[1]
Polyphyodonts include most toothed fishes, many reptiles such as crocodiles and geckos,[2][3][4] and most other vertebrates, mammals being the main exception.
New, permanent teeth grow in the jaws, usually under or just behind the old tooth, from stem cells in the dental lamina.[5] Young animals typically have a full set of teeth when they hatch; there is no tooth change in the egg. Within days, tooth replacement begins, usually in the back of the jaw continuing forward like a wave. On average a tooth is replaced every few months.
Crocodilia
Crocodilia are the only non-mammalian vertebrates with tooth sockets.[6]Alligators grow a successional tooth (a small replacement tooth) under each mature functional tooth for replacement once a year, each tooth being replaced up to 50 times in the alligator's life.[7] Crocodilia are researched for tooth regeneration in humans.[7]
Evolution in mammals
Manatees, elephants and kangaroos are unusual among mammals because they are polyphyodonts, in contrast to most other mammals which replace their teeth only once in their lives (diphyodont). Although most other extant mammals are not polyphyodont, mammalian ancestors were. During the evolution of Therapsida, there was a period during which mammals were so small and short-lived that wear on the teeth yielded no significant selection pressure to constantly replace them. Instead, mammals evolved different types of teeth which formed a unit able to crack the exoskeleton of arthropods. Molars came later in their evolution (as earlier in cerapods and Diplodocus[8]). Mammals chew (masticate) their food which requires a set of firmly attached, strong teeth and a "full" tooth row without gaps.
The manatees have no incisor or canine teeth, just a set of cheek teeth, which are not clearly differentiated into molars and premolars. These teeth are continuously replaced throughout their life with new teeth growing at the rear as older teeth fall out from farther forward in the mouth, a process known as "hind molar progression" or “marching molars”.[9]
^Fuenzalida, Marcela; Lemus, Susi; Illanes, Julio; Montiel, Enrique; Acuña, Olga; Lemus, David (2000). "Histochemical detection of sugar residues in lizard teeth (Liolaemus gravenhorsti): a lectin-binding study". Biological Research. 33 (3–4): 215–226. doi:10.4067/s0716-97602000000300008. PMID 15696682.
^Gaete, Marcia; Tucker, Abigail S. (3 September 2013). "Organized Emergence of Multiple-Generations of Teeth in Snakes Is Dysregulated by Activation of Wnt/Beta-Catenin Signalling". PLOS ONE. 8 (9): e74484. Bibcode:2013PLoSO...874484G. doi:10.1371/journal.pone.0074484. PMC3760860. PMID 24019968.
^Whitlock, John A; Richman, Joy M (June 2013). "Biology of tooth replacement in amniotes". International Journal of Oral Science. 5 (2): 66–70. doi:10.1038/ijos.2013.36. PMC3707075. PMID 23788284.
^LeBlanc, Aaron R. H.; Reisz, Robert R. (4 September 2013). "Periodontal Ligament, Cementum, and Alveolar Bone in the Oldest Herbivorous Tetrapods, and Their Evolutionary Significance". PLOS ONE. 8 (9): e74697. Bibcode:2013PLoSO...874697L. doi:10.1371/journal.pone.0074697. PMC3762739. PMID 24023957.
^ abWu, Ping; Wu, Xiaoshan; Jiang, Ting-Xin; Elsey, Ruth M.; Temple, Bradley L.; Divers, Stephen J.; Glenn, Travis C.; Yuan, Kuo; Chen, Min-Huey; Widelitz, Randall B.; Chuong, Cheng-Ming (28 May 2013). "Specialized stem cell niche enables repetitive renewal of alligator teeth". Proceedings of the National Academy of Sciences. 110 (22): E2009-18. Bibcode:2013PNAS..110E2009W. doi:10.1073/pnas.1213202110. PMC3670376. PMID 23671090.
^D’Emic, Michael D.; Whitlock, John A.; Smith, Kathlyn M.; Fisher, Daniel C.; Wilson, Jeffrey A. (17 July 2013). "Evolution of High Tooth Replacement Rates in Sauropod Dinosaurs". PLOS ONE. 8 (7): e69235. Bibcode:2013PLoSO...869235D. doi:10.1371/journal.pone.0069235. PMC3714237. PMID 23874921.
^. Archived from the original on 2016-03-03. Retrieved 2013-11-07.[unreliable source?]
Further reading
Tucker, Abigail S.; Fraser, Gareth J. (January 2014). "Evolution and developmental diversity of tooth regeneration" (PDF). Seminars in Cell & Developmental Biology. 25–26: 71–80. doi:10.1016/j.semcdb.2013.12.013. PMID 24406627.
Fraser, Gareth J.; Meredith Smith, Moya (15 March 2011). "Evolution of developmental pattern for vertebrate dentitions: an oro-pharyngeal specific mechanism". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 316B (2): 99–112. doi:10.1002/jez.b.21387. PMID 21328527.
March 27, 2023
polyphyodont, polyphyodont, animal, whose, teeth, continually, replaced, contrast, diphyodonts, characterized, having, only, successive, sets, teeth, nile, crocodile, crocodylus, niloticus, include, most, toothed, fishes, many, reptiles, such, crocodiles, geck. A polyphyodont is any animal whose teeth are continually replaced In contrast diphyodonts are characterized by having only two successive sets of teeth 1 Nile crocodile Crocodylus niloticus Polyphyodonts include most toothed fishes many reptiles such as crocodiles and geckos 2 3 4 and most other vertebrates mammals being the main exception Contents 1 Growth 2 Crocodilia 3 Evolution in mammals 4 See also 5 References 6 Further readingGrowth EditNew permanent teeth grow in the jaws usually under or just behind the old tooth from stem cells in the dental lamina 5 Young animals typically have a full set of teeth when they hatch there is no tooth change in the egg Within days tooth replacement begins usually in the back of the jaw continuing forward like a wave On average a tooth is replaced every few months Crocodilia EditCrocodilia are the only non mammalian vertebrates with tooth sockets 6 Alligators grow a successional tooth a small replacement tooth under each mature functional tooth for replacement once a year each tooth being replaced up to 50 times in the alligator s life 7 Crocodilia are researched for tooth regeneration in humans 7 Evolution in mammals EditManatees elephants and kangaroos are unusual among mammals because they are polyphyodonts in contrast to most other mammals which replace their teeth only once in their lives diphyodont Although most other extant mammals are not polyphyodont mammalian ancestors were During the evolution of Therapsida there was a period during which mammals were so small and short lived that wear on the teeth yielded no significant selection pressure to constantly replace them Instead mammals evolved different types of teeth which formed a unit able to crack the exoskeleton of arthropods Molars came later in their evolution as earlier in cerapods and Diplodocus 8 Mammals chew masticate their food which requires a set of firmly attached strong teeth and a full tooth row without gaps The manatees have no incisor or canine teeth just a set of cheek teeth which are not clearly differentiated into molars and premolars These teeth are continuously replaced throughout their life with new teeth growing at the rear as older teeth fall out from farther forward in the mouth a process known as hind molar progression or marching molars 9 See also Edit Medicine portalRegeneration biology Regenerative medicine Regenerative endodontics Schultz s rule Sinoconodon Squamata Tooth developmentReferences Edit Buchtova M Stembirek J Glocova K Matalova E Tucker A S May 2012 Early Regression of the Dental Lamina Underlies the Development of Diphyodont Dentitions Journal of Dental Research 91 5 491 498 doi 10 1177 0022034512442896 PMID 22442052 S2CID 206417026 Mechanism of tooth replacement in Leopard geckos Archived from the original on 2015 03 12 self published source Fuenzalida Marcela Lemus Susi Illanes Julio Montiel Enrique Acuna Olga Lemus David 2000 Histochemical detection of sugar residues in lizard teeth Liolaemus gravenhorsti a lectin binding study Biological Research 33 3 4 215 226 doi 10 4067 s0716 97602000000300008 PMID 15696682 Gaete Marcia Tucker Abigail S 3 September 2013 Organized Emergence of Multiple Generations of Teeth in Snakes Is Dysregulated by Activation of Wnt Beta Catenin Signalling PLOS ONE 8 9 e74484 Bibcode 2013PLoSO 874484G doi 10 1371 journal pone 0074484 PMC 3760860 PMID 24019968 Whitlock John A Richman Joy M June 2013 Biology of tooth replacement in amniotes International Journal of Oral Science 5 2 66 70 doi 10 1038 ijos 2013 36 PMC 3707075 PMID 23788284 LeBlanc Aaron R H Reisz Robert R 4 September 2013 Periodontal Ligament Cementum and Alveolar Bone in the Oldest Herbivorous Tetrapods and Their Evolutionary Significance PLOS ONE 8 9 e74697 Bibcode 2013PLoSO 874697L doi 10 1371 journal pone 0074697 PMC 3762739 PMID 24023957 a b Wu Ping Wu Xiaoshan Jiang Ting Xin Elsey Ruth M Temple Bradley L Divers Stephen J Glenn Travis C Yuan Kuo Chen Min Huey Widelitz Randall B Chuong Cheng Ming 28 May 2013 Specialized stem cell niche enables repetitive renewal of alligator teeth Proceedings of the National Academy of Sciences 110 22 E2009 18 Bibcode 2013PNAS 110E2009W doi 10 1073 pnas 1213202110 PMC 3670376 PMID 23671090 D Emic Michael D Whitlock John A Smith Kathlyn M Fisher Daniel C Wilson Jeffrey A 17 July 2013 Evolution of High Tooth Replacement Rates in Sauropod Dinosaurs PLOS ONE 8 7 e69235 Bibcode 2013PLoSO 869235D doi 10 1371 journal pone 0069235 PMC 3714237 PMID 23874921 Manatee adaptations the head Archived from the original on 2016 03 03 Retrieved 2013 11 07 unreliable source Further reading EditTucker Abigail S Fraser Gareth J January 2014 Evolution and developmental diversity of tooth regeneration PDF Seminars in Cell amp Developmental Biology 25 26 71 80 doi 10 1016 j semcdb 2013 12 013 PMID 24406627 Fraser Gareth J Meredith Smith Moya 15 March 2011 Evolution of developmental pattern for vertebrate dentitions an oro pharyngeal specific mechanism Journal of Experimental Zoology Part B Molecular and Developmental Evolution 316B 2 99 112 doi 10 1002 jez b 21387 PMID 21328527 Retrieved from https en wikipedia org w index php title Polyphyodont amp oldid 1107422463, wikipedia, wiki, book, books, library,
