Fig. 4. Light micrograph of a stage-9 ovariole with corresponding extracellular H⁺ fluxes superimposed. H⁺ flux is indicated by red vectors, with length proportional to the flux magnitude. Vector angles are the result of summing x- and y-axis measurements. Vectors traveling away from the ovariole surface represent H⁺ efflux; vectors traveling over the ovariole are influx. The noise measurement is in the bottom left corner. Of interest is the H⁺ efflux near the forming chorion rim in late vitellogenic oocytes (asterisk), which remains throughout choriogenesis. Red scale bar, 100 fmol cm^–2 s^–1; black scale bar, 100 µm.