The Second Wave of Neurogenesis in the DRG

成熟的背根节(DRG)是由大约20种不同类别的感觉组成的异质混合体。 除了神经胶质细胞外，还有神经元。这种不同的细胞类型阵列从 神经脊线仍未被完全理解。背根神经节中有两波神经发生。 第一波的祖细胞是迁移的神经脊细胞，这些细胞沿着腹侧迁移路径停止， 融合，并分化为本体感觉神经元和机械感觉神经元。第二波，谱写 主要是TrkA+的伤害性传入是在神经脊迁移停止后产生的。 最初，TrkA+神经元散布在新生的DRG中，但在3天内它们变得 戏剧性地局限于神经节的背侧内侧2/3。调节这一空间的机制 种族隔离是完全不被理解的。此外，导致第二次浪潮的祖代种群 仍然定义不清。这项提议的目标是识别和表征能够提供 上升到在第二波神经发生中出生的神经元，并通过时间推移共聚焦成像 显微镜下，当伤害性神经元在成熟的背根节内分化时，它们的诞生和行为。

The mature dorsal root ganglion (DRG) is a heterogeneous mixture of ca 20 different classes of sensory neurons in addition to glial cells. The mechanisms by which this diverse array of cell types derives from the neural crest remains incompletely understood. There are two waves of neurogenesis in the DRG. Progenitors for the first wave are migrating neural crest cells that stop along their ventral migration pathway, coalesce, and differentiate into proprioceptive and mechanoceptive neurons. The second wave, composed primarily of nociceptive afferents that are TrkA+, are bom after the cessation of neural crest migration. Initially TrkA+ neurons are dispersed throughout the nascent DRG, but within 3 days they become dramatically confined to the dorsal medial 2/3 of the ganglion. The mechanisms mediating this spatial segregation are not at all understood. Furthermore, the progenitor population that gives rise to the 2nd wave remains ill defined. The goals of this proposal are to identify and characterize the progenitor cells that give rise to neurons born during the 2nd wave of neurogenesis, and to image, via time-lapse confocal microscopy, the birth and behavior of nociceptive neurons as they differentiate within the maturing DRG.