Vertebrates possess paired cranial sensory ganglia derived from two embryonic cell populations, neural crest and placodes. Cranial sensory ganglia arose prior to the divergence of jawed and jawless vertebrates, but the developmental mechanisms that facilitated their evolution are unknown. Using gene expression and cell lineage tracing experiments in embryos of the sea lamprey, Petromyzon marinus, we find that in the cranial ganglia we targeted, development consists of placode‐derived neuron clusters in the core of ganglia, with neural crest cells mostly surrounding these neuronal clusters. To dissect functional roles of neural crest and placode cell associations in these developing cranial ganglia, we used CRISPR/Cas9 gene editing experiments to target genes critical for the development of each population. Genetic ablation of SoxE2 and FoxD‐A in neural crest cells resulted in differentiated cranial sensory neurons with abnormal morphologies, whereas deletion of DlxB in cranial placodes resulted in near‐total loss of cranial sensory neurons. Taken together, our cell‐lineage, gene expression, and gene editing results suggest that cranial neural crest cells may not be required for cranial ganglia specification but are essential for shaping the morphology of these sensory structures. We propose that the association of neural crest and placodes in the head of early vertebrates was a key step in the organization of neurons and glia into paired sensory ganglia.

中文翻译：

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神经lamp和斑code在七lamp鳗的颅感觉神经节的形成和模式中的作用。

脊椎动物具有配对的颅内感觉神经节，它们来自两个胚胎细胞群，神经sensor和斑块。颅内感觉神经节出现在有颚和无颚脊椎动物分化之前，但是促进它们进化的发育机制尚不清楚。使用基因表达和细胞谱系追踪实验在海七rey鱼（Petromyzon marinus）的胚胎中，我们发现在我们靶向的颅神经节中，发育由神经节核心中斑源性神经元簇组成，神经neural细胞主要围绕这些神经元簇。为了剖析这些发育中的颅神经节中神经c和斑节细胞协会的功能作用，我们使用了CRISPR / Cas9基因编辑实验来靶向对每个人群的发育至关重要的基因。SoxE2和FoxD ‐ A在神经c细胞中的遗传消融导致分化的颅感觉神经元具有异常形态，而DlxB缺失颅骨斑块中的蛋白质导致几乎全部颅骨感觉神经元丧失。综上所述，我们的细胞谱系，基因表达和基因编辑结果表明，颅神经rest细胞可能不是颅神经节规范所必需的，但对于塑造这些感觉结构的形态至关重要。我们提出，在早期脊椎动物头部中神经and和斑块的关联是将神经元和神经胶质组织成配对的感觉神经节的关键步骤。