Neurite-promoting factors from embryonic neurons.

Dissociated chick embryo peripheral and central nervous system cultures enriched for neurons by differential adherence, defined medium and cytosine arabinoside release to the culture environment molecular species which enhance the performance of neurons in limiting conditions. Culture medium conditioned by the neurons can be depleted of substrate-attached material by serial passage on poly-D-lysine substrate, leaving in the medium factors which promote neurite outgrowth on poly-D-lysine. The substrate-attached material which enhances neuron survival and neurite extension is heat- and trypsin-labile but is not affected by prior treatment with antisera to mouse NGF, human plasma fibronectin or laminin. The autostimulation phenotype displayed by neurons may play a role in neuronal survival or axonal growth during neuronal development.