The previtellogenic development of the oocyte is independent of juvenile hormone (JH), but for vitellogenesis JH is essential. The follicle cells at the lateral and apical aspects of the oocyte undergo different structural modifications in the normal mated females. The apical cells remain tall and closely apposed to each other, while lateral cells become spherical, binucleate and develop patency. In virgins also where corpus allatum is inactive the follicle cells become binucleate but their size remains small and they do not develop patency.