Fig. 4.

Controls, using retinas that were sectioned, processed, and displayed as in Figure 1. a,b, One pair of sections was cut from a light-adapted retina, then incubated with anti-cAMP antiserum (a) or with anti-cAMP antiserum that was preincubated in cAMP (b). c,d, Another pair of sections was cut from another light-adapted retina, then incubated with anti-cAMP antiserum that was preincubated in cGMP (c) or with anti-cAMP antiserum that was preincubated in cAMP (d).e, f, A third retina was dark-adapted and incubated for 30 min in darkness in 30 μm dopamine. Sections cut from this retina were incubated with anti-cAMP antiserum (e) or with anti-cAMP antiserum that was preincubated in cAMP (f). Magnification is identical in all panels. Scale bar, 30 μm.