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Development of the lamprey velum and implications for the evolution of the vertebrate jaw
Author(s) -
Yokoyama Hiromasa,
Yoshimura Miho,
Suzuki Daichi G.,
Higashiyama Hiroki,
Wada Hiroshi
Publication year - 2021
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/dvdy.243
Subject(s) - lamprey , biology , hindbrain , vertebrate , neural crest , anatomy , extant taxon , population , zebrafish , mandible (arthropod mouthpart) , evolutionary biology , neuroscience , genetics , zoology , gene , central nervous system , demography , fishery , sociology , genus
Background The vertebrate jaw is thought to have evolved through developmental modification of the mandibular arch. An extant jawless vertebrate, the lamprey, possesses a structure called “velum”—a mandibular arch derivative—in addition to the oral apparatus. This leads us to assess the velum's possible contribution to the evolution of jaws. Results The velar muscles develop from progenitor cells distinct from those from which the oral muscles develop. In addition, the oral and velar regions originate from the different sub‐population of the trigeminal neural crest cells (NCCs): the former region receives NCCs from the midbrain, whereas the latter region receives NCCs from the anterior hindbrain. The expression of patterning genes (eg, DlxA and MsxA ) is activated at a later developmental stage in the velum compared to the oral region , and more importantly, in different cells from those in the oral region. Conclusion The lamprey mandibular arch consists of two developmental units: the anterior oral unit and the posterior velar unit. Because structural elements of the lamprey velum may be homologous to the jaw, the evolution of vertebrate jaws may have occurred by the velum being released from its functional roles in feeding or respiration in jawless vertebrates.