TNF-α enhances growth of rat derived neurospheres. (A) Photographs of neurospheres, 1 (upper panel) and 4 (lower panel) days after plating, show larger neurospheres after TNF treatment than in control neurospheres. Note that 10 ng/ml TNF has the greatest size induction effect. Bar, 200 μm. (B) Quantification of neurosphere volume. TNF-treated neurospheres show significantly increased volume compared to untreated neurospheres (*** P < 0.0001, **P < 0.05).