An autoradiographic study on the origin and fate of the sub‐pial glioblast in the embryonic chick spinal cord

Gliogenesis in the spinal cord was studied in chick embryos ranging in age from 3 to 14 days of incubation using H3‐thymidine autoradiography. It has been reported by the author that the neuron production of the spinal cord begins on the third day and ends at the eighth day of incubation. At eight days of incubation glioblasts with small dark round nuclei first appear in the sub‐pial region. Using the selective labeling technique with H3‐thymidine the author demonstrated that no transition exists from pial cells to sub‐pial glioblasts. The glioblasts are produced from the matrix cells by their migration and transformation. These glioblasts mature into neuroglia (oligodendroglia and astrocytes), as development proceeds. The suggestion that the stage of neuroglia differentiation follows that of neuron production in development of the central nervous system has been reconfirmed.