Fig. 4.

(A) GAP43 is expressed in the ventral, lateral and dorsal funiculi and in the GM. Nestin-immunoreactive radial glial cells still radiate from the central canal to the pial surface. (B) Radial glial cells exhibit a high degree of branching at the GM/WM interface (arrows), but remain evenly distributed in the WM. (C) The densities of radial glial cell processes in the ventral and dorsal WM are maintained throughout the rostrocaudal axis of the spinal cord. (D) The mean densities of radial glial cells in both the rostral (*P < 0.05) and caudal (⁺P < 0.05) WM are significantly reduced from E14 to E16, and from E16 to E18, in line with axon tract formation. (E) The combined mean densities of radial glial cell processes in all regions of the WM decline significantly from E14 to E16, and from E16 to E18 (*^,**P < 0.05). (F) Western blot showing vimentin and GAP43 expression from E14 to P6. β-actin was used as a control. (G) Densitometrical analysis showing how GAP43-immunoreactive axons increase postnatally, while vimentin-immunoreactive radial glial cells decline. (Both images are confocal projections of 15–20 images captured at 0.5-μm intervals. Scale bars are in microns as indicated, the dorsoventral orientation is consistent for B as indicated in A).