Formation of a glial scar following microinjection of fetal neurons into the hippocampus or midbrain of the adult rat: an immunocytochemical study.

Raphe tissue (minced or dissociated) from fetal rat was microinjected into adult hippocampus or midbrain, and the response of astrocytes observed by immunocytochemical staining for the astrocyte specific marker, glial fibrillary acidic protein (GFA). Astrocytes were observed to form a border around the transplanted cells. This border was visible as early as 7 days post-transplant and was still present up to 6 months later. The transplanted serotonergic cells, identified by immunocytochemical staining with a primary antibody to serotonin, appeared at the edge of the border but not beyond. This border may be responsible for preventing the complete integration of the transplanted cells with the adult host hippocampal and midbrain tissue.