Sympathetic reinnervation of the rat iris in organ culture.

Reinnervation of sympathetically denervated rat iris by superior cervical ganglion cells has been demonstrated to occur in vitro. Return of [(3)H]norepinephrine uptake by irises incubated in contact with ganglia was associated with the reappearance of nerve fibers containing catecholamines that were demonstrable by fluorescent histochemistry. The reinnervating neurons appeared to follow the same general pattern of innervation seen in the normal iris, but the density of the neural plexus was much greater. Nerve growth factor influenced the rate and extent of innervation of the iris but not of neuronal growth within the ganglion.