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发育中的脊椎动物的感觉神经元在它们的轴突到达靶区后对神经趋向因子(neurotrophic factors)变得依赖起来。对四组鸡胚胚板起源的感觉性脑神经元进行研究,揭示了这一变化过程,即这些神经元的轴突穿越不同的距离才抵达外周及中枢的靶区(结状节的神经元走的距离最长,以后依次分别为岩节、膝状节、前庭神经节神经元)。虽然距靶区远的神经元的轴突生长要快些,但是它们到达靶区的时间还是要比那些离靶区近的神经元到达的时间长。在体外,神经趋向因子非依赖性生存的持续时间及神经趋向因子依赖性的开始的时间与体内神经到达并支配靶区的时间过程是相关的:那些靶区近、先支配靶区的神经元(前庭神经节神经元)在没有对来源于脑的神经趋向因子(BDNF)反应前只生存短时间,而靶区较
Sensory neurons in developing vertebrates become dependent on neurotrophic factors after their axons reach the target area. The study of four groups of sensory brain neurons originating from chicken embryo plate revealed the process by which axons of these neurons cross different distances to reach the peripheral and central target regions (nodose ganglion neurons Walk the longest distance, followed by rock section, knee section, vestibular ganglion neurons). Although neurons far from the target area grow faster than axons in the target area, they reach the target area longer than those reaching the target area. In vitro, the duration of neurotactic factor-independent survival and the initiation of neurotrophic factor dependence correlate with the time course of neurons reaching and dominating the target zone in vivo: those that target the target zone and predominate the target zone (Vestibular ganglion neurons) survived for only a short time without response to brain-derived neurotrophic factor (BDNF), whereas the target area