Fig. 3. irk2 expression in principal cells of the tubule main segment and spermatheca. (A) Low-power view, showing the expression in the spermatheca (SP), but not in other areas, including the rectum (RE). (B) Expression in the tubules along the length of the main segment (MS) but not in the initial segment (IS) of the anterior tubule. (C) High-power view of the IS showing no staining. Sense controls did not produce any staining (data not shown). Tubule diameter can be taken as 35 µm throughout.