Motoneuron death and motor unit size during embryonic development of the rat
Motoneuron death and motor unit size during embryonic development of the rat
复制标题
大鼠胚胎发育过程中运动神经元死亡和运动单位大小
DOI：
10.1523/jneurosci.04-01-00013.1984
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
C. McCaig
中科院分区：
文献类型：
--
作者：
A. Harris;C. McCaig
大鼠胚胎在出生前最后4 ~ 6天的慢性瘫痪导致骨骼肌纤维数量减少，但抑制运动神经元死亡。因此，随着瘫痪肌肉的发育，越来越多的运动神经元试图在数量减少的突触部位形成突触。瘫痪的肌肉纤维在单个终板上接收突触，就像控制肌肉一样，但是这些终板是神经过度支配的，输入的数量大约是正常的两倍。轴突、突触输入和肌肉单位的计数表明，运动神经元通常在出生前不久接触最大数量的肌纤维，并且这个数量在出生后的几天内保持稳定，直到它最终减少到成人数量。瘫痪胚胎在出生时的平均运动单位大小与对照组相同。我们认为，这是没有必要的假设胚胎神经末梢之间的竞争的存在，以解释调节最初接触的运动神经元的肌纤维的数量。运动神经元的死亡并没有立即受到瘫痪的影响，但瘫痪“拯救”了所有运动神经元，这些运动神经元的死亡通常会发生在瘫痪开始后24小时或更长时间，无论何时发生。这意味着决定死亡的高峰期是在胚胎第14天，此时肌管形成刚刚开始，肌肉中没有可识别的终板结构。当瘫痪时，通常注定死亡的运动神经元能够形成正常数量的功能性神经肌肉接触。
Chronic paralysis of rat embryos during the last 4 to 6 prenatal days causes a diminution in skeletal muscle fiber numbers but inhibits motoneuron death. Consequently, as paralyzed muscles develop, an increased number of motoneurons attempts to form synapses at a reduced number of synaptic sites. Paralyzed muscle fibers receive their synapses at a single endplate, as in control muscles, but these endplates are hyperinnervated, with about twice the normal number of inputs. Counts of axons, synaptic inputs, and muscle units showed that motoneurons normally contact a maximum number of muscle fibers shortly before birth, and this number remains stable for several days postnatal until it finally is reduced to the adult number. The average motor unit size in paralyzed embryos at the time of birth was the same as in controls. We suggest that it is not necessary to postulate the existence of competition between embryonic nerve terminals in order to explain regulation of the number of muscle fibers initially contacted by a motoneuron. Motoneuron death was not immediately affected by paralysis, but paralysis “rescued” all motoneurons whose death normally would have occurred 24 hr or more after the time when paralysis was initiated, regardless of when this was. This implies that the peak period for determination to die is during embryonic day 14, when myotube formation is just beginning and no recognizable endplate structures are present in muscles. When paralyzed, motoneurons normally destined to die are capable of forming a normal number of functional nerve-muscle contacts.
神经系统发育的遗传方法的优点和缺点。
影响因子：
13.9
作者：
Stent,GS
通讯作者：
Stent,GS