ULTRASTRUCTURAL OBSERVATIONS ON SYNAPSE ELIMINATION IN NEONATAL RABBIT SKELETAL-MUSCLE
ULTRASTRUCTURAL OBSERVATIONS ON SYNAPSE ELIMINATION IN NEONATAL RABBIT SKELETAL-MUSCLE
复制标题
DOI：
10.1007/bf01181746
复制
发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
BIXBY, JL
中科院分区：
文献类型：
--
作者：
BIXBY, JL
为了研究哺乳动物的神经肌肉发育，利用家兔骨骼肌的EM来确定新生儿突触的消除是通过突触终端和前终端轴突的退化进行的，还是通过类似于轴突生长锥的吸收过程将终端缩回到母体轴突中；并找出多余突触的消除和末梢轴突的髓鞘形成之间的关系。通过固定在突触消除高峰时间的终板检查数百个切片，未发现退行性变迹象。根据新生儿神经横断后末梢变性的时间进程计算，这一结果与突触消除的主要机制是末梢变性的说法不一致。末端和前末端轴突的连续和半连续重建表明，肌内轴突的髓鞘形成滞后于突触的消除，当轴突与雪旺细胞的关系尚未成熟时，突触的消除可以进行。通过新生儿突触的序列切片重建显示，它们的三维结构比成熟的神经肌肉突触更复杂，表明早期神经和肌肉之间可能存在动态关系。
To study mammalian neuromuscular development, EM of rabbit skeletal muscle was used to determine if neonatal synapse elimination proceeds by the degeneration of synaptic terminals and preterminal axons, or if the terminals are retracted into the parent axon in a process analogous to the resorption of axonal growth cones; and to identify any discernible relationship between the elimination of supernumerary synapses and the myelination of preterminal axons. Examination of serveral hundred sections through endplates fixed at the peak time of synapse elimination revealed no signs of degeneration. This result is not consistent with the proposal that the major mechanism of synapse elimination is terminal degeneration, according to calculations based on the time course of terminal degeneration following neonatal nerve transection. Serial and semi-serial reconstruction of terminals and preterminal axons suggest that myelination of intramuscular axons lags behind synapse elimination and that elimination can proceed while axons bear an immature relationship to Schwann cells. Reconstruction of serial sections through neonatal synapses revealed that their 3-dimensional configuration is more complex than that of mature neuromuscular synapses, indicating a possible dynamic relationship between nerve and muscle at early stages.