In Triturus administration of NGF causes hypertrophy of neuronal perikarya of third dorsal root ganglia and post-subclavian sympathetic ganglia.
Two classes of neurons were characterized cytologically in the third dorsal root ganglia. Some evidence is presented which indicates that Class I neurons respond more vigorously to NGF. It is suggested that Class I neurons are similar to the medio-dorsal neuroblasts of chick embryos in their response to NGF.
Forelimb amputation did not cause neuronal hypertrophy in either third dorsal root ganglia or post-subclavian sympathetic ganglia.
The incorporation of (3H)-uridine increases to a highly significant extent in third dorsal root ganglia following NGF treatment or limb amputation. When NGF treatment and limb amputation were combined, no further increase in (3H)-uridine incorporation was noted. This suggests that RNA synthesis is maximally stimulated by either NGF treatment alone or limb amputation alone.