Nievelstein R A, Hartwig N G, Vermeij-Keers C, Valk J
Department of Diagnostic Radiology, Free University Hospital, Amsterdam, The Netherlands.
Teratology. 1993 Jul;48(1):21-31. doi: 10.1002/tera.1420480106.
In the literature, some controversy still exists about the embryonic developmental processes involved in the formation of the caudal neural tube. Therefore, a three-dimensional and histological study concerning the normal development of the caudal neural tube was performed on both mouse and human embryos. Three developmental processes can be distinguished in caudal neural tube development: caudal neuropore closure, secondary neurulation, and degeneration and differentiation of the secondary neural tube. Caudal neuropore closure occurs at the level of somite 32-34 in both species. Therefore, primary neurulation leads to the formation of all spinal cord segments and ganglia. Secondary neurulation involves cell deposition from a cluster of neurectodermal cells at the caudal end of the closed neural tube, directly around a lumen, the lumen always in contact with the lumen of the primary neural tube. This process leads only to the formation of the primordia of the filum terminale and ventriculus terminalis and, possibly, part of the conus medullaris. Secondary neurulation is followed by a period characterized by degeneration and differentiation of the secondary neural tube. Its lumen and neural tissue will disappear, whereas part of the secondary neurectodermal cells differentiate to a fibrous layer comparable and continuous with the marginal layer of the primary neural tube. This fibrous layer represents the future filum terminale. The embryological processes indicated above can be helpful in the interpretation of congenital anomalies affecting the caudal spinal cord and spine.
在文献中，关于尾侧神经管形成所涉及的胚胎发育过程仍存在一些争议。因此，对小鼠和人类胚胎进行了一项关于尾侧神经管正常发育的三维和组织学研究。在尾侧神经管发育过程中可区分出三个发育过程：尾侧神经孔闭合、继发性神经胚形成以及继发性神经管的退化和分化。在这两个物种中，尾侧神经孔闭合均发生在第32 - 34体节水平。因此，原发性神经胚形成导致所有脊髓节段和神经节的形成。继发性神经胚形成涉及来自封闭神经管尾端一群神经外胚层细胞的细胞沉积，直接围绕一个管腔，该管腔始终与原发性神经管的管腔相连。这个过程仅导致终丝和终室原基的形成，以及可能的脊髓圆锥部分的形成。继发性神经胚形成之后是一个以继发性神经管的退化和分化为特征的时期。其管腔和神经组织将消失，而部分继发性神经外胚层细胞分化为与原发性神经管边缘层可比且连续的纤维层。这个纤维层代表未来的终丝。上述胚胎学过程有助于解释影响尾侧脊髓和脊柱的先天性异常。
