Nerve growth factors in the rat iris

Abstract
Nerve growth factor (NGF) activity was not detected by bioassay in irides killed immediately after excision, but NGF appeared within 24 h in living irides placed in culture or grafted to a host eye. Sensory and, although less effective, sympathetic denervation of irides in situ led to the appearance of NGF activity within 10 days. Freezing and thawing released a parasympathetic neuronotrophic factor activity from irides.