Neuronal Network Formation in the Spinal Cord of Chick Spina Bifida

正常的神经管闭合被认为是脊髓神经网络形成的主要因素。因此，手术引入的脊柱裂（SB）胚胎将使我们能够阐明神经网络形成的控制机制。(1)本研究通过重新打开一次闭合的神经管来发育鸡SB胚胎，并与正常胚胎的脊髓进行比较。(2) SB胚胎脊髓重开区结构异常；也就是说，中央管仍然向后表面开放，背角位于腹角之外。(3) SB脊髓TUNEL阳性神经元数量在重新开放后4 ~ 6 d达到高峰。(4) SB脊髓突触数量少于正常脊髓相同区域突触数量的一半。这些结果表明，人工修饰可能抑制了重新打开区域背角到腹角的神经连接。众所周知，人类SB患者表现出不同程度的神经功能缺陷，如感觉丧失。进一步，我们将分析我们的SB模型脊髓的上游连接。

The normal neural tube closure is thought to be a principal factor on the neural network formation in the spinal cord. Therefore, embryos with Spina Bifida (SB), which is surgically introduced, will enable us to clarify the controlling mechanism of the neural network formation.(1) In the present study, we developed chick SB embryos according to reopen the neural tube that had closed once, and compared the spinal cords of SB with those of normal embryos.(2) The reopened regions of the spinal cords in SB embryos showed the abnormal structure ; that is the central canal was still opened to the back surface and the dorsal horn was located outside the ventral horn.(3) The number of TUNEL positive neurons in the SB spinal cord reached its peak 4 to 6 days after reopening.(4) The number of the synapses in the SB spinal cord was smaller than half of that in the same regions of the normal spinal cord.These results suggested that the neural connections from dorsal horn to ventral horn in the reopened region might be inhibited by the artificial modification. It is known that human SB patients shows varying degrees of neurological deficit as loss of sensation. Further, we will analyze the upstream connection in the spinal cords of our SB models.