Influence of ganglion age,nonneuronal cells and substratum on neurite outgrowth in culture

This study characterizes the outgrowth patterns of superior cervical ganglia (SCG) obtained from embryonic (E15), perinatal (E20–21), and adult (P35) rats when placed in culture on various substrata. Outgrowth morphology, degree of fasciculation, and outgrowth length were examined on collagen (COL), polyornithine (PO), polylysine (PL), fibronectin (FN), and nonneuronal cells (NNCs) from the ganglion. COL and FN supported extensive neuritic outgrowth; PO and PL provided poor support. Outgrowth pattern, degree of fasciculation, neurite growth rate, and the number of NNCs in the outgrowth varied considerably depending upon the COL configuration. When undiluted COL (～5 mg/ml) was air dried, a three-dimensional loose fibrillar network was formed. Upon COL dilution or gelling undiluted COL by ammoniation, an essentially two-dimensional layer was formed. On two-dimensional COL, NNCs were able to proliferate and migrate extensively from ganglia of all ages; their presence influenced the form and extent of neurite growth. E15, E20, and P35 neurites responded differently to their endogenous NNCs. E15 neurites extended in relation to NNC surfaces and were predominantly nonfasciculated. E20 neurites became more fasciculated in the presence of NNCs that exhibited morphological and behavioral differences from those migrating from E15 ganglia. E20 neurite bundles became defasciculated when they extended into E15 outgrowth. Far fewer neurites grew from P35 explants in the presence of their NNCs. Three-dimensional COL greatly slowed NNC migration and thus allowed investigation of neurite outgrowth from ganglia of differing age in the absence of NNCs. We conclude that neuritic outgrowth patterns on varying substrata reflect not only neurite differences depending upon ganglion age but also variation in the behavior of accompanying NNCs.