EFFECTS OF ULTRASOUND ON NEURONAL DEVELOPMENT

这项研究将确定超声波对形成的影响， 特定的神经元连接，这是一个正常的过程， 神经系统的功能。 在正常发育过程中，许多现象包括神经元迁移， 分化，轴突生长作出重要贡献， 神经细胞支配的最终模式。 拟议的研究将 探讨超声波对三个关键发育阶段的影响， 过程：1）神经嵴细胞的迁移，2）突起 轴突生长的模式和时间; 3）特异性突触形成。 的 在这些研究中使用的模型系统将是交感神经 小鸡的系统。 交感神经系统特别适合于此 研究，因为它提供了一个不太复杂的系统相比，中央 神经系统和广泛的发育研究已经完成。 选择鸡胚具有明显的优点：1）“卵内” 胚胎是一个独立的系统，不受环境的影响。 母体宿主，因此直接与致畸剂反应; 2） 鸡的交感神经系统与哺乳动物的交感神经系统相似;以及3） 鹌鹑细胞可作为研究神经嵴迁移的天然标记物。 将使用的技术非常敏感， 检测超声波的致畸作用 用一只小鹌鹑 移植技术，神经嵴细胞的迁移模式将 被确定。 辣根过氧化物酶（HRP）轴突的利用 追踪技术允许轴突的时间和投射模式 需要精确识别的结果。 此外，细胞内记录 技术将用于确定特定神经节细胞的模式， 神经支配

This study will determine the effects of ultrasound on the formation of specific neuronal connections, a process that is essential for the normal functioning of the nervous system. During normal development, many phenomena including neuronal migration, differentiation, and axon outgrowth make important contributions to the final pattern of nerve cell innervations. The proposed research will investigate the effect of ultrasound on three critical developmental processes: 1) the migration of neural crest cells, 2) the projection pattern and timing of axonal growth, 3) specific synapse formation. The model system used in these investigations will be the sympathetic nervous system of the chick. The sympathetic system is especially suited to this study as it provides a less complex system compared with the central nervous system and extensive developmental studies have already been done. The chick embryo was chosen for obvious advantages: 1) The "in ovo" embryo, being an independent system is not influenced by the condition of a maternal host and, therefore, reacts directly to teratogenic agents; 2) The sympathetic system of the chick is similar to that of the mammal; and 3) Quail cells can be used as natural markers to study neural crest migration. The techniques that will be used are extremely sensitive and will readily detect any teratogenic effects of ultrasound. Using a quail-chick transplanation technique, the migration pattern of neural crest cells will be determined. Utilization of a horseradish peroxidase (HRP) axonal tracing technique allows the timing and projection patterns of axonal outgrowth to be precisely identified. In addition, intracellular recording techniques will be used to determine the pattern of specific ganglion cell innervation.