Fig. 4. Micrographs of sections from the adult retina following in situ hybridization with the UV and blue riboprobes after variable proteinase K incubation times. (A–F) Serial sections from the mid-ventro-temporal retina show that the coho UV riboprobe (coUV) does not label cones after 5 min (A,D) or 13 min (B,E) of proteinase K exposure, and this is the same result as obtained using the rainbow trout UV riboprobe (rtUV) after 13 min of proteinase K exposure (C,F). (G,H) Serial tangential (G) and radial (H) sections corresponding to those in A–F show that all single cones are labelled by the blue riboprobe (rtBL) after 10 min of proteinase K treatment. The riboprobes used and the time of proteinase K exposure (in parentheses) are shown at the bottom of each panel. Note that proteinase K exposure times used by Allison et al. (Allison et al., 2003) for the rainbow trout UV and blue riboprobes were 13 min and 10 min, respectively. Other symbols and nomenclature as in Fig. 2. Magnification bar (in A) is 25 µm and relates to all panels.