Origins of the pituitary gland Placodes are specializations of the head ectoderm that are considered the source of many vertebrate novelties, including the nose, lens, ear, and hormone-producing portion of the pituitary. However, the presence of a pituitary-like structure in nonvertebrate chordates, derived instead from the endoderm, had suggested that the pituitary may predate placodes. Fabian et al. performed lineage tracing, time-lapse imaging, and single-cell messenger RNA sequencing to show that both endodermal and ectodermal cells can generate hormone-producing cells of the zebrafish pituitary. These experiments support that the vertebrate pituitary arises through interactions of an ancestral endodermal protopituitary with newly evolved placodal ectoderm. Science, this issue p. 463 Fate mapping in developing zebrafish reveals that pituitary development mixes ectodermal and endodermal progenitors. Vertebrate sensory organs arise from epithelial thickenings called placodes. Along with neural crest cells, cranial placodes are considered ectodermal novelties that drove evolution of the vertebrate head. The anterior-most placode generates the endocrine lobe [adenohypophysis (ADH)] of the pituitary, a master gland controlling growth, metabolism, and reproduction. In addition to known ectodermal contributions, we use lineage tracing and time-lapse imaging in zebrafish to identify an endodermal contribution to the ADH. Single-cell RNA sequencing of the adult pituitary reveals similar competency of endodermal and ectodermal epithelia to generate all endocrine cell types. Further, endoderm can generate a rudimentary ADH-like structure in the near absence of ectodermal contributions. The fish condition supports the vertebrate pituitary arising through interactions of an ancestral endoderm-derived proto-pituitary with newly evolved placodal ectoderm.

中文翻译：

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谱系分析揭示了内胚层对脊椎动物垂体的贡献


脑垂体的起源 基板是头部外胚层的特化，被认为是许多脊椎动物新奇事物的来源，包括鼻子、晶状体、耳朵和垂体产生激素的部分。然而，非脊椎动物脊索动物中存在类似垂体的结构，而不是源自内胚层，这表明垂体可能早于基板。法比安等人。进行了谱系追踪、延时成像和单细胞信使 RNA 测序，结果表明内胚层和外胚层细胞都可以产生斑马鱼垂体产生激素的细胞。这些实验支持脊椎动物垂体是通过祖先内胚层原垂体与新进化的盾板外胚层相互作用而产生的。科学，本期第 14 页。 463 发育中的斑马鱼的命运图谱表明，垂体发育混合了外胚层和内胚层祖细胞。脊椎动物的感觉器官由称为基板的上皮增厚物产生。与神经嵴细胞一样，颅板被认为是外胚层的新奇事物，推动了脊椎动物头部的进化。最前面的基板产生垂体的内分泌叶[腺垂体（ADH）]，这是控制生长、代谢和繁殖的主腺。除了已知的外胚层贡献之外，我们还使用斑马鱼的谱系追踪和延时成像来确定内胚层对 ADH 的贡献。成人垂体的单细胞 RNA 测序揭示了内胚层和外胚层上皮细胞产生所有内分泌细胞类型的相似能力。此外，内胚层可以在几乎没有外胚层贡献的情况下产生基本的 ADH 样结构。 鱼类的条件支持脊椎动物的垂体是通过祖先内胚层衍生的原垂体与新进化的板外胚层相互作用而产生的。