MAMMALIAN MYOGENESIS SUBSEQUENT TO FETAL DENERVATION

体内肌生成与发育同时发生， 胎儿神经系统的成熟。因为哺乳动物的胎儿 很容易被操纵，我们对神经肌肉的了解 发展过程中的关系已经从发展的研究中获得， 小妞最近的研究表明，哺乳动物的神经肌肉关系 胎儿可能与小鸡不同。一种新技术， 切除胎儿的腰骶区，鼠脊髓， 而不干扰胎儿的生存能力和进一步成熟， 为了确定胎儿去神经支配对肌管形成的影响， 哺乳动物肌管存活和肌管多样性的产生 肌肉.将使用电子显微镜、定量 形态计量学、凝胶电泳和免疫细胞化学。这些研究 将提供有关基因决定的改变的信息， 由环境因素引起的肌生成模式（即，发展中 运动神经元）。很少有人知道轴突切断术的影响，在 不同的胎儿阶段，对哺乳动物运动神经元的生存。技术 其允许横断脊神经的腹根或 坐骨神经将允许确定哺乳动物轴突是否可以 存活轴突切断术和是否（以及在什么条件下），他们可以支配 横纹肌如果切断轴突的运动神经元存活， 神经支配和/或短暂胎儿去神经支配对肌肉发育的影响将 进行评估。如果它们不能存活， 部分去神经支配的成年肌肉的运动神经元池 将确定胎儿发育的时间。评价将与 电子显微镜，生理学和通过检查小鼠的脊髓 他们的肌肉被注射了HRP拟议的研究与以下方面有关： 人类发展

In vivo myogenesis occurs simultaneously with the development and maturation of the fetal nervous system. Because the mammalian fetus has not been easily manipulated, much of what we know about nerve-muscle relationships during development has been gained from studies of developing chick. Recent studies suggest that nerve-muscle relationships in mammalian fetuses may differ from those in chick. A new technique which permits laser ablation of the lumbosacral region of the fetal, murine spinal cord, without interfering with fetal viability and further maturation, will allow us to determine the effect of fetal denervation on myotube formation, myotube survival and on the generation of myotube diversity in mammalian muscles. Evaluations will be made with electron microscopy, quantitative morphometry, gel electrophoresis and immunocytochemistry. These studies will provide information concerning alterations in genetically determined patterns of myogenesis by an environmental factor (i.e., the developing motoneuron). Little is known about the effects of axotomy, performed at various fetal stages, on the survival of mammalian motoneurons. Techniques which permit transection of the ventral roots of spinal nerves or of the sciatic nerve will allow determination of whether mammalian axons can survive axotomy and whether (and under what conditions) they can innervate striated muscle. If axotomized motoneurons survive, the effect of delayed innervation and/or transient fetal denervation on muscle development will be assessed. If they fail to survive, alterations in the size and location of motoneuron pools to adult muscles subjected to partial denervation during fetal development will be determined. Evaluations will be made with electron microscopy, physiology and by examining the spinal cords of mice whose muscles were injected with HRP. The proposed studies are relevant to human development.