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Evolutionary developmental studies of cyclostomes and the origin of the vertebrate neck
Author(s) -
Kuratani Shigeru
Publication year - 2008
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.2008.00985.x
Subject(s) - vertebrate , lamprey , biology , evolutionary biology , hagfish , anatomy , evolutionary developmental biology , neural crest , embryology , comparative anatomy , zoology , embryo , genetics , paleontology , gene
Because they lack some gnathostome‐specific traits, cyclostomes have often been regarded as representing an intermediate state linking non‐vertebrate chordates and gnathostomes. To understand the evolutionary origins of the jaw and paired fins, lamprey embryos and larvae have been used as comparative models. The lack of the jaw–neck region is a conspicuous feature specific to cyclostomes; however, the absence of these features has been largely neglected both in evolutionary developmental studies and in the field of classical comparative embryology. This review seeks to develop a possible evolutionary scenario of the vertebrate neck muscles by taking the cucullaris (trapezius) muscle as the focus. By combining the comparative embryology of lampreys and gnathostomes, and considering the molecular‐level developmental mechanism of skeletal muscle differentiation, this review argues that the establishment of the vertebrate neck deserves to be called an evolutionary novelty based on the remodeling of mesenchymal components between the cranium and the shoulder girdle, which involves both mesodermal and neural crest cell lineages.