Mazet Francoise
School of Biological Sciences, AMS Building, Whiteknights, PO Box 228, Reading, RG6 6AJ, UK.
ScientificWorldJournal. 2006 Apr 4;6:1841-50. doi: 10.1100/tsw.2006.314.
The vertebrate cranial sensory placodes are ectodermal embryonic patches that give rise to sensory receptor cells of the peripheral paired sense organs and to neurons in the cranial sensory ganglia. Their differentiation and the genetic pathways that underlay their development are now well understood. Their evolutionary history, however, has remained obscure. Recent molecular work, performed on close relatives of the vertebrates, demonstrated that some sensory placodes (namely the adenohypophysis, the olfactory, and accoustico-lateralis placodes) first evolved at the base of the chordate lineage, while others might be specific to vertebrates. Combined with morphological and cellular fate data, these results also suggest that the sensory placodes of the ancestor of all chordates differentiated into a wide range of structures, most likely to fit the lifestyle and environment of each species.
脊椎动物的颅感觉基板是外胚层胚胎斑块，可产生外周成对感觉器官的感觉受体细胞以及颅感觉神经节中的神经元。它们的分化以及其发育所依据的遗传途径现在已得到充分了解。然而，它们的进化历史仍然模糊不清。最近对脊椎动物近亲进行的分子研究表明，一些感觉基板（即腺垂体、嗅觉和听侧线基板）最早是在脊索动物谱系的基部进化而来的，而其他一些可能是脊椎动物特有的。结合形态学和细胞命运数据，这些结果还表明，所有脊索动物祖先的感觉基板分化成了广泛的结构，最有可能是为了适应每个物种的生活方式和环境。
