FEATURES HISTOGENESIS NEUROEPITELIAL LAYER OF THE SPINAL CORD OF HUMAN EMBRYOS AND FETUSES

Aim. To investigate the histogenesis of the neuroepithelial layer of the human spinal cord in the prenatal period of ontogenesis. Materials and Methods. An anatomical and histological study of 12 spinal cords of human embryos aged 5-7 weeks of fetal development and 173 fetuses within gestational period of 8 to 40 weeks prenatal period of ontogenesis. Results and Discussion. In embryos of 5-7 weeks the thickness of the neuroepithelial layer gradually increases in dorsal direction and an increased proliferation of neural stem cells (NSC) in the dorsal part of the neuroepithelial layer is observed. The average area of the NSC is 47,9±2,1 mkm2, core area - 24,6±1,5 mkm2. Radial glial fibers expressing the protein vimentin pass from the basement membrane of the neuroepithelium radially through the mantle layer and penetrate into the edge layer. We also found that in addition to vimentin, radial glial fibers were expressing the protein CDX-2. In fetuses of 9-10 weeks the thickness of the neuroepithelial layer is actually the same throughout the perimeter of the center channel; however, the intensity of NSC proliferation begins to increase in the ventral part. After 12 weeks the thickness of the neuroepithelial layer is higher in the ventral part, where there is also an increase in the intensity and NSC proliferation. In the mantle layer the fibers of the radial glia were relatively poorly expressed. At 22-23 weeks of high expression of vimentin is observed in radial glial fibers, which are concentrated on both sides of the front and rear walls of the medial segments of the spinal cord, and focal expression of vimentin in radial glial fibers around blood vessels in the mantle layer of the spinal cord is seen. In fetuses of 35-36 weeks the average size of NSC, which form the neuroepithelium is equal to 30,5±1,3 mkm2, and the core area of NSC - 17,7±0,8 mkm2. It should be noted that the cell proliferation of NSC neuroepithelial layer is of a focal character. Conclusions. During the prenatal period of ontogenesis, the area and thickness of the neuroepithelial layer of the spinal cord undergoes changes, as well as the area of the NSC and their nuclei. Keywords: spinal cord, neuroepithelial layer, the radial glia, neural stem cells