collagen as adherent substratum and inducer of dorsal root ganglia outgrowth

neurite outgrowth from dorsal root ganglion (drg) explants is a method of evaluating neurotrophic activity of growth factors. when complete medium containing collagen was supplemented with nerve growth factor (ngf) drg outgrowth was observed after 18 h. in the absence of ngf and in the presence of collagen, the drg outgrowth took place after 72 h. in wells not supplemented with collagen gel in substratum, no drg outgrowth was observed. partially, drg differentiation was observed in the presence of ngf. in the absence of ngf and collagen, there was no drg outgrowth detected. it seems that, in some circumstances, cells degenerated by drg may be an indication of an apoptosis phenomenon. therefore, we suggested that collagen as a substratum is more effective than ngf