Kuratani Shigeru, Oisi Yasuhiro, Ota Kinya G
1 Laboratory for Evolutionary Morphology, RIKEN, Kobe 650-0047, Japan.
2 Development and Function of Inhibitory Neural Circuits, Max Planck Florida Institute for Neuroscience, One Max Planck Way, Jupiter, FL 33458-2906, USA.
Zoolog Sci. 2016 Jun;33(3):229-38. doi: 10.2108/zs150187.
Our knowledge of vertebrate cranium evolution has relied largely on the study of gnathostomes. Recent evolutionary and developmental studies of cyclostomes have shed new light on the history of the vertebrate skull. The recent ability to obtain embryos of the hagfish, Eptatretus burgeri, has enabled new studies which have suggested an embryonic morphological pattern (the "cyclostome pattern") of craniofacial development. This pattern is shared by cyclostomes, but not by modern jawed vertebrates. Because this pattern of embryonic head development is thought to be present in some stem gnathostomes (ostracoderms), it is possible that the cyclostome pattern represents the vertebrate ancestral pattern. The study of cyclostomes may thus lead to an understanding of the most ancestral basis of craniofacial development. In this review, we summarize the development of the hagfish chondrocranium in light of the cyclostome pattern, present an updated comparison of the cyclostome chondrocranium, and discuss several aspects of the evolution and development of the vertebrate skull.
我们对脊椎动物颅骨进化的了解在很大程度上依赖于对有颌类动物的研究。近期对圆口纲动物的进化和发育研究为脊椎动物头骨的历史带来了新的启示。最近获得盲鳗（Eptatretus burgeri）胚胎的能力使得新的研究得以开展，这些研究提出了一种颅面发育的胚胎形态模式（“圆口纲模式”）。这种模式为圆口纲动物所共有，但现代有颌脊椎动物却没有。由于这种胚胎头部发育模式被认为存在于一些原始有颌类动物（甲胄鱼）中，所以圆口纲模式有可能代表了脊椎动物的祖先模式。因此，对圆口纲动物的研究可能会让我们了解颅面发育最原始的基础。在这篇综述中，我们根据圆口纲模式总结了盲鳗软骨颅的发育情况，对圆口纲软骨颅进行了更新的比较，并讨论了脊椎动物头骨进化和发育的几个方面。
