Fig. 11.

The red indicates the NO-IF that was present in salamander following 10 min of stimulation with 50 μm nicotine before fixation. The green indicates the NO-IF that was present following 30 min of paraformaldehyde fixation. The yellow indicates the NO-IF that was present before and after fixation. There is virtually no pure green in the image indicating that fixation did not induce or create any NO-IF that was not there prior to fixation. The red over the photoreceptors indicates that much of the NO-IF in the photoreceptors was lost during fixation. Scale bar, 20 lm.