Influence of nerve growth factor on the embryonic mouse trigeminal ganglion in culture

Developing trigeminal ganglia have been excised from mouse embryos of 9, 10, 11 and 12 days gestation and grown in tissue culture. A quantitative method was used to assess the effect of nerve growth factor (NGF) and an antiserum to NGF (anti-NGF) on fiber outgrowth from the explanted ganglia. Fiber outgrowth from 9-day ganglia (E9 ganglia) appeared to be unaffected by the presence of NGF. However, the ganglia became increasingly responsive to NGF from embryonic day 10 through 12. The increased responsiveness to NGF in vitro coincided with the establishment of fiber contacts with peripheral target tissues in vivo. Anti-NGF produced no significant reduction of fiber outgrowth from E9 ganglia, but from later ganglia significant reduction were observed.