Wound healing following stab injury on rat cerebral cortex

We examined how wound healing was initiated and completed. Stab injury was made over the right parietal cortex with 2.5 mm depth and 4 mm length. Either 3 days, 7 days or 1 month after this operation, operated rats were perfused and fixed with 4% paraformaldehyde. The brains were removed, embedded in paraffin, cut coronally at a level of caudate-putamen complex and thin-sliced into 6 microns thick sections with a microtome. The sections were stained immunohistochemically for detection of glial fibrillary acidic protein (GFAP), and co-stained for myelination with Woelcke's staining method. Sections were also stained immunohistochemically for Laminin after pretreatment by pepsin. Furthermore, the sections were stained either haematoxylin-eosin staining, Laidlaw's Reticulum staining for evaluation of reticulin and phosphotungusten acid haematoxylin (PTAH) staining for delination of collagen. We, first, confirmed astrocytic proliferation induced by the stab injury. Then, astrocytes can be seen crowded around the injured site 7 days after injury. Both Laminin and Reticulum stain show the so-called neovascularization around the stab wound 7 days after injury when astrocytes proliferated most vigorously as mentioned above. PTAH stain showed collagenous fibre 1 month after injury when astrocytes congregated along the wound site, and Laminin fibres were localized to the injury site. Reticulin fibres disappeared. In conclusion, it takes more than a month for the wound site to regain the steady state.