Raible David W, Ungos Josette M
Department of Biological Structure, University of Washington, Seattle, Washington, USA.
Adv Exp Med Biol. 2006;589:170-80. doi: 10.1007/978-0-387-46954-6_10.
How distinct cell fates are generated from initially homogeneous cell populations is a driving question in developmental biology. The neural crest is one such cell population that is capable of producing an incredible array of derivatives. Cells as different in function and form as the pigment cells in the skin or the neurons and glia of the peripheral nervous system are all derived from neural crest. How do these cells choose to migrate along distinct routes, populate defined regions of the embryo and differentiate into specific cell types? This chapter focuses on the development of one particular neural crest derivative, sensory neurons, as a model for studying these questions of cell fate specification. In the head, sensory neurons reside in the trigeminal and epibranchial ganglia, while in the trunk they form the spinal or dorsal root ganglia (DRG). The development of the DRG will be the main focus of this review. The neurons and glia of the DRG derive from trunk neural crest cells that coalesce at the lateral edge of the spinal cord (Fig. 1). These neural crest cells migrate along the same routes as neural crest cells that populate the autonomic sympathetic ganglia located along the dorsal aorta. Somehow DRG precursors must make the decision to stop and adopt a sensory fate adjacent to the spinal cord rather than continuing on to become part of the autonomic ganglia. Moreover, once the DRG precursors aggregate in their final positions there are still a number of fate choices to be made. The mature DRG is composed of many neurons with different morphologies and distinct biochemical properties as well as glial cells that support these neurons.
最初均一的细胞群体如何产生不同的细胞命运，这是发育生物学中的一个核心问题。神经嵴就是这样一种细胞群体，它能够产生一系列令人难以置信的衍生物。功能和形态差异极大的细胞，比如皮肤中的色素细胞或者外周神经系统中的神经元和神经胶质细胞，都源自神经嵴。这些细胞如何选择沿着不同的路径迁移，在胚胎的特定区域聚集并分化为特定的细胞类型呢？本章聚焦于一种特定的神经嵴衍生物——感觉神经元的发育，以此作为研究细胞命运特化问题的模型。在头部，感觉神经元位于三叉神经节和鳃上神经节，而在躯干中，它们形成脊髓或背根神经节（DRG）。DRG的发育将是本综述的主要关注点。DRG中的神经元和神经胶质细胞源自聚集在脊髓外侧边缘的躯干神经嵴细胞（图1）。这些神经嵴细胞沿着与那些形成沿背主动脉分布的自主交感神经节的神经嵴细胞相同的路径迁移。不知何故，DRG前体细胞必须做出决定，在脊髓附近停止迁移并采用感觉命运，而不是继续迁移成为自主神经节的一部分。此外，一旦DRG前体细胞在其最终位置聚集，仍有许多命运选择要做。成熟的DRG由许多具有不同形态和独特生化特性的神经元以及支持这些神经元的神经胶质细胞组成。
