Is the vertebrate head segmented?-evolutionary and developmental considerations.
Is the vertebrate head segmented?-evolutionary and developmental considerations.
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DOI：
10.1093/icb/icn015
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发表时间：
2008-11
影响因子：
2.6
通讯作者：
Kuratani S
中科院分区：
文献类型：
--
作者：
Kuratani S
由于七鳃鳗胚胎在脊椎动物系统发育树上的基础位置，因此推测七鳃鳗胚胎具有分节头中胚层。然而，最近的观察表明，七鳃鳗头部没有任何体节样的节段。腔肠头腔是最明显的板鳃类胚胎，似乎并不代表普遍的脊椎动物的特征。从生殖约束的角度来看，脊椎动物体内的节段结构可以分为初级节段和次级节段，初级节段作为节段性胚胎原基出现，如体节和咽囊，次级节段的模式由初级节段的存在决定。次级节包括最初不分节的神经嵴衍生物和上鳃基板。脊椎动物的头部中胚层被次级区域化为几个域，这些域不对其他结构施加任何次级节段模式。因此，脊椎动物头部的特点是缺乏节段性生殖约束在其中胚层。经典的体节理论现在被驳斥了，因为他们试图将脊椎动物的头部等同于文昌鱼的头部，文昌鱼的吻体节被认为是脊椎动物中不存在的初级体节。
Because of its basal position on the phylogenetic tree of vertebrates, the lamprey embryo would be expected to exhibit segmental head mesoderm. Recent observations, however, show that the lamprey does not have any somite-like segments in the head. Coelomic head cavities that are most conspicuous in elasmobranch embryos, do not appear to represent universal vertebrate traits. From the perspective of generative constraint, segmental structures in the vertebrate body can be classified into primary segments, which arise as segmental embryonic primordia such as somites and pharyngeal pouches, and secondary segments whose patterns are determined by the presence of primary segments. Secondary segments include neural crest derivatives and epibranchial placodes that are not initially segmented. The head mesoderm of vertebrates is secondarily regionalized into several domains that do not impose any secondary segmental patterns on other structures. Thus, the vertebrate head is characterized by a lack of segmental generative constraint in its mesoderm. Classical segmental theories are now refuted because they attempted to equate the vertebrate head with that of the amphioxus, whose rostral somites are considered primary segments, which are absent from vertebrates.
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影响因子：
64.8
作者：
GUTHRIE, S;MUCHAMORE, I;LUMSDEN, A
通讯作者：
LUMSDEN, A
影响因子：
2.4
作者：
Graham, A
通讯作者：
Graham, A
影响因子：
64.8
作者：
FRASER, S;KEYNES, R;LUMSDEN, A
通讯作者：
LUMSDEN, A
影响因子：
--
作者：
Detwiler, SR
通讯作者：
Detwiler, SR
影响因子：
64.8
作者：
FIGDOR, MC;STERN, CD
通讯作者：
STERN, CD