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Text
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URL Address
<a href="http://doi.org/10.1111/joa.12579" target="_blank" rel="noreferrer noopener">http://doi.org/10.1111/joa.12579</a>
Pages
549–566
Issue
4
Volume
230
Dublin Core
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Title
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Evolutionary aspects of the development of teeth and baleen in the bowhead whale.
Publisher
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Journal of anatomy
Date
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2017
2017-04
Subject
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*Biological Evolution; Animals; baleen; baleen whales; bowhead whale; Bowhead Whale/anatomy & histology/*embryology; Cetacea; Dentition; embryology; Female; FGF; Jaw/anatomy & histology/embryology; keratin; Mixed; Mouth/anatomy & histology/*embryology; mysticetes; ontogeny; Pregnancy; tooth development; Tooth/anatomy & histology/*embryology
Creator
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Thewissen J G M; Hieronymus Tobin L; George John C; Suydam Robert; Stimmelmayr Raphaela; McBurney Denise
Description
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In utero, baleen whales initiate the development of several dozens of teeth in upper and lower jaws. These tooth germs reach the bell stage and are sometimes mineralized, but toward the end of prenatal life they are resorbed and no trace remains after birth. Around the time that the germs disappear, the keratinous baleen plates start to form in the upper jaw, and these form the food-collecting mechanism. Baleen whale ancestors had two generations of teeth and never developed baleen, and the prenatal teeth of modern fetuses are usually interpreted as an evolutionary leftover. We investigated the development of teeth and baleen in bowhead whale fetuses using histological and immunohistochemical evidence. We found that upper and lower dentition initially follow similar developmental pathways. As development proceeds, upper and lower tooth germs diverge developmentally. Lower tooth germs differ along the length of the jaw, reminiscent of a heterodont dentition of cetacean ancestors, and lingual processes of the dental lamina represent initiation of tooth bud formation of replacement teeth. Upper tooth germs remain homodont and there is no evidence of a secondary dentition. After these germs disappear, the oral epithelium thickens to form the baleen plates, and the protein FGF-4 displays a signaling pattern reminiscent of baleen plates. In laboratory mammals, FGF-4 is not involved in the formation of hair or palatal rugae, but it is involved in tooth development. This leads us to propose that the signaling cascade that forms teeth in most mammals has been exapted to be involved in baleen plate ontogeny in mysticetes.
Identifier
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<a href="http://doi.org/10.1111/joa.12579" target="_blank" rel="noreferrer noopener">10.1111/joa.12579</a>
Rights
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
*Biological Evolution
2017
Animals
baleen
baleen whales
bowhead whale
Bowhead Whale/anatomy & histology/*embryology
Cetacea
Dentition
Department of Anatomy & Neurobiology
embryology
Female
FGF
George John C
Hieronymus Tobin L
Jaw/anatomy & histology/embryology
Journal of anatomy
keratin
McBurney Denise
Mixed
Mouth/anatomy & histology/*embryology
mysticetes
NEOMED College of Medicine
ontogeny
Pregnancy
Stimmelmayr Raphaela
Suydam Robert
Thewissen J G M
tooth development
Tooth/anatomy & histology/*embryology