Figure 1. Neuronal protein immunoexpression in fetal organotypic explants. A, Survey micrograph of untreated explant has weak MAP-2 staining of cortical neurites. B, Sister explant treated with 50 ng/ml VEGF has intensely stained and thickened MAP-2+ neurites extending to the edge of the culture. C, Higher magnification shows that the effects on MAP-2+ neurite growth compared with control explants can be recognized after 10 ng/ml VEGF. MAP-2+ processes are of moderate intensity, but neuronal soma staining, which was not observed in control explants, can be discerned (arrow). D, Application of 100 ng/ml VEGF to the fetal explants induces robust MAP-2 immunoexpression typical of mature cortical neurons. E, Untreated (control) fetal cortical explant has weak immunoexpression of NSE, a developmentally regulated neuronal glycolytic enzyme. F, Sister explant to E treated with 100 ng/ml VEGF has a substantial increase in NSE immunoexpression and a much improved organizational appearance of the explant neuropil that was not seen in the controls or at low VEGF doses. NSE expression is representative of neuronal metabolic activity and the explant neurons had a variable staining intensity as occurs in situ. Scale bar: (in F) A, B, 140 μm; C, D, 100 μm; E, F, 120 μm.