Neuronal Network Formation in the Spinal Cord of Chick Spina Bifida

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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.