Fladby T, Jansen J K
Acta Physiol Scand. 1987 Feb;129(2):239-46. doi: 10.1111/j.1748-1716.1987.tb08064.x.
The present work aims to distinguish between processes that lead to neonatal synapse elimination. We have partially denervated the mouse soleus muscle just after birth by cutting one (L5) of the two (L4 and L5) spinal nerves which supply its innervation. After 4-6 weeks' survival times, we determined the number of remaining motor units (MUs) and the number of innervated fibres in the muscle by conventional physiological and histological techniques. There was no significant overlap between the remaining MUs. Their average size was reduced from about 230 muscle fibres at birth to about 80 after 4-6 weeks, compared to only 30 in normal animals of the same age. We conclude that two processes are required to explain synapse elimination in the muscle: a non-competitive process, inherent to the immature motor neurons and leading to a substantial reduction in their field of innervation; a competitive process between axon terminals innervating the same muscle fibre.
本研究旨在区分导致新生儿突触消除的过程。我们在小鼠出生后立即切断支配比目鱼肌的两条（L4和L5）脊神经中的一条（L5），从而部分去神经支配该肌肉。在存活4 - 6周后，我们通过传统的生理学和组织学技术确定了剩余运动单位（MU）的数量以及肌肉中受神经支配的纤维数量。剩余的运动单位之间没有明显重叠。它们的平均大小从出生时约230条肌纤维减少到4 - 6周后的约80条，而同龄正常动物中仅为30条。我们得出结论，需要两个过程来解释肌肉中的突触消除：一个是非竞争性过程，这是未成熟运动神经元固有的，导致其支配区域大幅减少；另一个是支配同一肌纤维的轴突终末之间的竞争性过程。
