Origin and segregation of cranial placodes in Xenopus laevis
Origin and segregation of cranial placodes in Xenopus laevis
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DOI：
10.1016/j.ydbio.2011.09.024
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发表时间：
2011-12-15
影响因子：
2.7
通讯作者：
Schlosser, Gerhard
中科院分区：
文献类型：
--
作者：
Pieper, Mareike;Eagleson, Gerald W.;Schlosser, Gerhard
颅基板是脊椎动物头部外胚层的局部增厚，其有助于成对的感觉器官（嗅上皮、透镜、内耳、侧线）、颅神经节和腺垂体。在这里，我们使用组织移植和染料注射产生的非神经外胚层爪蟾胚胎的神经板和早期尾芽阶段之间的背颅部分的命运地图。我们发现，所有的基板产生于一个新月形的区域位于周围的前神经板，基板前外胚层。在协议中提出的作用Six 1和Pax基因的规格panplacodal原基和不同的基板领域，分别，我们表明，Six 1是均匀地表达在整个大部分的前基板外胚层，而Pax 6，Pax 3，Pax 8和Pax 2每个都局限于特定的子区域，包括不同子集的基板的前体。然而，前体的迷走神经鳃上和后侧线基板，从posteriormost前基板外胚层，上调Six 1和Pax 8/Pax 2只在尾芽阶段。而我们的命运地图表明，不同的基板的起源区域相互重叠，并与其他外胚层的命运在神经板阶段，共同标记基板的分析表明，实际的重叠程度要小得多。时间推移成像的前基板我外胚层在单细胞分辨率表明，没有定向，大规模的细胞重排发生时，前基板区域分离成不同的基板在随后的阶段。我们的研究结果表明，个性化的基板前基板外胚层不涉及大规模的细胞分选爪蟾。(C)2011 Elsevier Inc. All rights reserved.
Cranial placodes are local thickenings of the vertebrate head ectoderm that contribute to the paired sense organs (olfactory epithelium, lens, inner ear, lateral line), cranial ganglia and the adenohypophysis. Here we use tissue grafting and dye injections to generated fate maps of the dorsal cranial part of the non-neural ectoderm for Xenopus embryos between neural plate and early tailbud stages. We show that all placodes arise from a crescent-shaped area located around the anterior neural plate, the pre-placodal ectoderm. In agreement with proposed roles of Six1 and Pax genes in the specification of a panplacodal primordium and different placodal areas, respectively, we show that Six1 is expressed uniformly throughout most of the pre-placodal ectoderm, while Pax6, Pax3, Pax8 and Pax2 each are confined to specific subregions encompassing the precursors of different subsets of placodes. However, the precursors of the vagal epibranchial and posterior lateral line placodes, which arise from the posteriormost pre-placodal ectoderm, upregulate Six1 and Pax8/Pax2 only at tailbud stages. Whereas our fate map suggests that regions of origin for different placodes overlap extensively with each other and with other ectodermal fates at neural plate stages, analysis of co-labeled placodes reveals that the actual degree of overlap is much smaller. Time lapse imaging of the pre-placoda I ectoderm at single cell resolution demonstrates that no directed, large-scale cell rearrangements occur, when the pre-placodal region segregates into distinct placodes at subsequent stages. Our results indicate that individuation of placodes from the pre-placodal ectoderm does not involve large-scale cell sorting in Xenopus. (C) 2011 Elsevier Inc. All rights reserved.