Eide A L, Glover J C
Department of Physiology, University of Oslo, Norway.
Brain Res Dev Brain Res. 1996 Nov 22;97(1):126-37. doi: 10.1016/s0165-3806(96)00140-x.
The possibility that muscle sensory afferents that enter the spinal cord at different segmental levels compete for terminal space in the lateral motor column was tested by unilaterally ablating neural crest cells destined to generate dorsal root ganglia (DRGs). Newly migrating neural crest was surgically removed from several lumbosacral segments on one side of the spinal cord on day 3 of embryogenesis (d3). The resultant experimental preparations developed without DRGs on the operated side at the segmental levels where the ablation was performed. At d18 the central projection from the intact DRG immediately caudal to the operated segments was anatomically mapped with a lipophilic axonal tracer. The central projection from the same DRG on the opposite, unoperated side was mapped as a control. The density of terminals along the longitudinal axis of the lateral motor column was quantified in serial sections with an image analysis program. On both the operated and control sides, the majority of terminals were found within the segment of entry and the rostral and caudal neighboring spinal segments. However, the rostral neighboring segment received a larger proportion of terminals on the operated side compared to the control side. Thus, the absence of primary afferents entering the spinal cord at specific segments leads to a shift of the afferent projection to the lateral motor column from the neighboring segments towards the deafferented segments.
通过单侧切除注定要生成背根神经节（DRG）的神经嵴细胞，来测试在不同节段水平进入脊髓的肌肉感觉传入神经在外侧运动柱中竞争终末空间的可能性。在胚胎发育第3天（d3），从脊髓一侧的几个腰骶节段手术切除新迁移的神经嵴。在进行切除的节段水平，所得到的实验标本在手术侧没有发育出DRG。在d18时，用亲脂性轴突示踪剂对紧邻手术节段尾侧的完整DRG的中枢投射进行解剖学定位。对相对的未手术侧相同DRG的中枢投射进行定位作为对照。使用图像分析程序在连续切片中对沿外侧运动柱纵轴的终末密度进行量化。在手术侧和对照侧，大多数终末都位于进入节段以及相邻的头侧和尾侧脊髓节段内。然而，与对照侧相比，手术侧头侧相邻节段接受的终末比例更大。因此，特定节段没有初级传入神经进入脊髓会导致传入投射从相邻节段向去传入神经节段转移至外侧运动柱。
