Figure 6

Figs. 6A and 6B show the distal stumps of sciatic nerves 30 days (A) and 8 days (B) after resection of a piece of the nerve. ATF3+ nuclei (green) are found in cells that co-express the Schwann cell markers S100 (red in A) and p75 (red in B). The arrows indicate some of the nuclei clearly situated in cytoplasm expressing the Schwann cell markers. Fig. 6C is a double exposure showing a phase contrast image and ATF3 immunofluorescence (green) of a distal stump of a nerve 4 days after resection. ATF3+ nuclei are found between debris-laden macrophages (*) inside bands of Büngner (one of which is outlined by arrows). Figs. 6D and 6E show sciatic nerve dorsal rootlets immunoreacted for ATF3 and GFAP, 8 days after dorsal rhizotomy. The dorsal root entry zone of the spinal cord (d) can be identified by its content of GFAP+ astrocytes (red) which extend processes into the peripheral part of the rootlets (*). ATF3 expression is largely confined to the peripheral rootlet where Schwann cells are found. Fig. 6F shows a dorsal rootlet immunoreacted for c-Jun (green) and GFAP (red) 24 hours after dorsal rhizotomy. The pattern of c-Jun expression precisely follows that of ATF3 (compare with Fig. 6E), being confined to the peripheral, Schwann cell-containing part of the rootlet (*) and being absent from the dorsal root entry zone (d). Figs. 6G and 6H are taken from a rat in which the left optic nerve was crushed 30 days previously, and are immunoreacted for ATF3 (green) and GFAP (red). In Fig. 6G the injury site (L) is marked by reduced GFAP staining. Some nuclei in the lesion are clearly ATF3+ and some cells within the optic nerve tissue proximal and distal to the lesion are very weakly ATF3+ but the expression is much weaker than in damaged peripheral nerves. Fig. 6H is taken from the retina of the same animal, and shows ATF3+ nuclei in the ganglion cell layer (arrowheads). Op = optic nerve head. Magnification bars = 25 μm in A-C; 100 μm in D and G; and 50 μm in E, F and H.