Reaction of oligodendrocytes and astrocytes to trauma and implantation. A combined autoradiographic and immunohistochemical study.

Small excision wounds were made in the parietooccipital cortex of adult mice, and in some of the animals a variety of fetal and adult tissues were implanted into the defect. The response of the oligodendrocytes to trauma and implantation was studied autoradiographically and immunohistochemically and compared to that seen in other glia. The results following trauma alone resembled those seen following implantation. Within 3 days of the surgery a marked proliferative response was seen in mature oligodendrocytes, as judged by uptake of tritiated thymidine in the nuclei, both around the wound and at distant sites extending even into the opposite hemisphere. Labeled astrocytes, microglia (macrophages), and endothelial cells were also found in the same distribution. Immunohistochemical examination using the myelin proteins, myelin basic protein and myelin-associated glycoprotein, failed to show any difference in staining characteristics from normal, in contrast to the marked increase in glial fibrillary acidic protein accompanying the division of astrocytes. The results of this experiment demonstrate that mature oligodendrocytes can proliferate and undergo mitosis in response to nonspecific damage to the central nervous system, in a manner similar to that seen with other glia. This response is, however, not linked to a nonspecific production of myelin proteins, which obviously require some other stimulus for their production.