Detection of a light-sensitive pool of cGMP in goldfish cone color receptors by immunocytochemistry. 
A procedure for the immunocytochemical localization of cGMP in the goldfish retina is described.  The procedure is then used to evaluate the presence of cGMP in cone color receptors in retinas from dark-adapted and light stimulate fish.  The results show that cone color receptors in dark-adapted retinas contain large amounts of immunocytochemically defined cGMP in the ellipsoid region, which are greatly reduced after light exposure.