ZFIN ID: ZDB-PUB-080825-8
The midline, oral ectoderm, and the arch-0 problem
Kimmel, C.B., and Eberhart, J.K.
Date: 2008
Source: Integrative and Comparative Biology 48(5): 668-680 (Journal)
Registered Authors: Eberhart, Johann, Kimmel, Charles B.
Keywords: none
MeSH Terms: none
PubMed: none Full text @ Integr. Comp. Biol.
ABSTRACT
In most versions of theories of the segmentation of the vertebrate head, a premandibular segment is present rostral to the jaw-forming mandibular segment. These theories posit that in ancient fishes this segment included a gill and a gill-supporting skeleton, which then was modified to support the anterior brain. However, we find no recent evidence for existence of such a premandibular segment. Rather, new findings from studies of fate mapping and gene expression show that the "premandibular" territory is in fact the maxillary region of the mandibular arch. A signaling cascade, beginning with dorsal midline mesoderm in the gastrula and relayed through neural ectoderm and then oral ectoderm, greatly expands the skeletal derivatives of maxillary neural crest in a manner fully consistent with the Gans–Northcutt theory of the vertebrate new head.
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