Fig. 1. Trout cytoplasmic carbonic anhydrase (tCAc) mRNA localization in the gills of rainbow trout (Oncorhynchus mykiss) by in situ hybridization. The images present two sets (A,B and C,D) of in situ hybridization results from serial sections of the gill incubated with probe (A,C), no probe (B) or probe in the presence of excess unlabelled probe (D) and are typical of the sections examined. Strong hybridization signals for tCAc are evident in epithelial cells of the lamellae at both low (A) and high (C) magnification. Scale bars, 40 µm (A,B) and 20 µm (C,D).