Neural-crest cells and neuromesodermal progenitors (NMPs) are multipotent cells that are important for development of vertebrate embryos. In embryos of ascidians, which are the closest invertebrate relatives of vertebrates, several cells located at the border between the neural plate and the epidermal region have neural-crest-like properties; hence, the last common ancestor of ascidians and vertebrates may have had ancestral cells similar to neural-crest cells. However, these ascidian neural-crest-like cells do not produce cells that are commonly of mesodermal origin. Here we showed that a cell population located in the lateral region of the neural plate has properties resembling those of vertebrate neural-crest cells and NMPs. Among them, cells with Tbx6-related expression contribute to muscle near the tip of the tail region and cells with Sox1/2/3 expression give rise to the nerve cord. These observations and cross-species transcriptome comparisons indicate that these cells have properties similar to those of NMPs. Meanwhile, transcription factor genes Dlx.b, Zic-r.b and Snai, which are reminiscent of a gene circuit in vertebrate neural-crest cells, are involved in activation of Tbx6-related.b. Thus, the last common ancestor of ascidians and vertebrates may have had cells with properties of neural-crest cells and NMPs and such ancestral cells may have produced cells commonly of ectodermal and mesodermal origins.

神经嵴细胞和神经中胚层祖细胞（NMP）是多能细胞，对脊椎动物胚胎的发育非常重要。海鞘是脊椎动物最接近的无脊椎动物亲戚，在其胚胎中，位于神经板和表皮区域之间边界的几个细胞具有神经嵴样特性。因此，海鞘和脊椎动物的最后共同祖先可能具有类似于神经嵴细胞的祖先细胞。然而，这些海鞘神经嵴样细胞不产生通常中胚层来源的细胞。在这里，我们发现位于神经板外侧区域的细胞群具有类似于脊椎动物神经嵴细胞和 NMP 的特性。其中，具有Tbx6相关表达的细胞有助于尾部尖端附近的肌肉，而具有Sox1/2/3表达的细胞则产生神经索。这些观察结果和跨物种转录组比较表明这些细胞具有与 NMP 相似的特性。同时，转录因子基因Dlx.b、Zic-rb和Snai让人想起脊椎动物神经嵴细胞中的基因回路，它们参与Tbx6 相关的激活。因此，海鞘和脊椎动物的最后共同祖先可能具有具有神经嵴细胞和NMP特性的细胞，并且此类祖先细胞可能产生通常具有外胚层和中胚层起源的细胞。