Comparison of the morphological effects of acidic and basic fibroblast growth factors on rat astroblasts in culture

The effect of acidic and basic fibroblast growth factors (aFGF and bFGF) on the morphology of cultured rat astroblasts and on the expression of glial fibrillary acidic protein (GFAP) were compared. The addition of either aFGF or bFGF affected the morphology of the flat, irregular, polygonal‐shaped astroblasts, which formed processes and acquire a fibrous appearance. Appreciable different morphological aspects were observed between aFGF‐ and bFGF‐induced cells, essentially between 11 and 14 days in culture. In the presence of bFGF the astroglial cells were more fibrous with a more compact perikaryon as compared to aFGF treated cells. At the ultrastructural level abundant intermediate filaments were observed in astroglial cells as an effect of aFGF and rare filaments but numerous microtubules were seen in bFGF‐treated cells. The immunoreactivity for GFAP increased with time in culture and was much stronger in aFGF‐treated cells compared to bFGF‐treated cells at day 14. An intense positive staining was observed in the somata of the astroglial cells and their processes in the presence of aFGF, while essentially the processes were stained in the presence of bFGF. After 21 days in culture GFAP immunoreaction was also found in the perikarya of cells treated with bFGF. These results show that rat astroglial cells respond somewhat differently to aFGF and bFGF.