Spatial and temporal transcellular current patterns during oogenesis.

We have used the two-dimensional vibrating probe to examine spatial and temporal patterns in the transcellular current flow around telotrophic ovarioles of the insect Rhodnius prolixus. We demonstrate a dynamic pattern of currents which correlates with various stages of vitellogenesis. Asymmetries exist in the radial current pattern around intact ovarioles, particularly around the terminal follicle, and may correlate with early developmental axes. The extra-cellular current pattern is largely reflected by a similar, though weaker pattern of currents over the germ cell membranes, indicating that both germ cell and somatic cell membranes are involved in current generation. Current enters previtellogenic oocytes and leaves oocytes entering vitellogenesis. We speculate that current reversal and loss of trophic cord contact may represent an electrophysiological feedback control mechanism during oogenesis.