Figure 1: Endogenous repaired tissue in cross section from injury epicenter (6 weeks after 25 mm contusion; H.E. staining). A, the repaired tissue located at the dorsal part of damaged cord, connects bilaterally to the spared tissue, and neighbors the lesion cavity, which is surrounded by the glial scar (arrows) and spared tissue. B, under higher magnification, the repaired tissue can be divided into three different zones: fibrotic, cellular, and axonal. The fibrotic zone is surrounded by a U-shape cellular zone. The axonal zone does not appear clearly due to its small amount of axons at this moment. C, the cellular zone, connecting to both spared tissue (*) and fibrotic zone, consists mainly of Schwann cells migrating from dorsal root (arrowheads). D, regenerating axons (myelinated fibers) with H.E. staining are difficult to identify at the axonal zone (arrowheads), cellular zone, and fribrotic zones (arrows). DR: dorsal root; VR: ventral root. Magnifications: 4x (A), 10x (B), 20x (C), 40x (D). (Replicated from Zhang, 2011 with permission)