Fig. 3. Mean extracellular H⁺ fluxes along adult Rhodnius ovarioles. (A) H⁺ flux magnitude and direction (influx/efflux) relative to position along ovariole and ovariole stage (N=10–18, shown in parentheses). The data for each ovariole stage, represented by fluctuating black lines running through the coloured region of the plot, are superimposed on each other making it difficult to show stage differences. However these are clearly discerned in a top view as seen in (B). The colour coding indicates H⁺ flux magnitude and direction, which is calibrated in B. Each vertical column on the surface plot corresponds to a specific point along the ovariole as indicated by the ovariole images. The leftmost column displays background noise. Horizontal rows display the average H⁺ flux for each ovariole stage (see Materials and methods). Prominent efflux occurs near the interfollicular stalks on either side of the T follicle. H⁺ efflux at the anterior stalk is greatest around stage 4 (early vitellogenesis) and declines gradually until stage 8 (late vitellogenesis) when it is significantly diminished. Stage-8 ovarioles were also characterized by the appearance of H⁺ influx along the anterior columnar epithelium of the T follicle.