At the time of analysis, the degree of responsiveness to EGF and bFGF as indicated by proliferation rate, was determined by plating undissociated aDRG NSCs into a six-well culture dish (Nunc) containing DMEM/F-12 media plus random assignment to treatment, including EGF, bFGF, or EGF + bFGF (10 ng/ml); we did not use untreated control groups because NSCs are not known to survive without trophic factor supplementation. The number of neurospheres per well was counted and standardized to approximately 250 ± 50 neurospheres. Neurospheres were counted on day 7 and 14 using the criteria stated below.
