Drawing of the closing neural tube, with the anterior and posterior neuropores still open
Drawing of the closing neural tube, with the anterior and posterior neuropores still open
Fusion of the neural tube begins in the cervical region and proceeds in both the cephalad and caudal directions, forming anterior and posterior neuropores. The anterior neuropore closes on the 25th day after conception; closure of the posterior neuropore normally occurs approximately two days later.