|
|
During week 4, the neural groove closes to form a neural tube beginning in the region of the 4th - 6th somites; fusion of neural folds proceeds cranially and caudally forming the brain and spinal cord respectively. Ectodermal cells of the early tube develop 3 concentric zones, 1) germinal (or matrix), 2) mantle, and 3) marginal. Cells of the original single-layered tube divide to form a pseudostratified neuroepithelium whose cells extend from the neural canal to the tube’s external surface. Cells near the central canal are called the germinal layer. They divide rapidly, thickening the walls of the tube and eventually producing neuroblasts and glioblasts.
Move the mouse
here to show all labels
| |||||||||||
