AbstractAzure B staining of Cecropia moth ovarian follicles indicated that the pattern of RNA concentrations characteristic of vitellogenic oocytes is disrupted by a gross redistribution and dispersion, beginning with the final discharge of the cytoplasm of the nurse cells into the oocyte. The cytoplasmic redistribution is largely complete two days later when chorion formation begins, the germinal vesicle breaks down, and the first meiotic spindle forms.At this stage the follicle contains 30 μg of RNA, of which 27 μg are in the follicle cells and only 3 μg in the oocyte itself. The proportionately large amount of follicle cell RNA apparently reflects the synthetic functions of these cells in the formation of yolk and the secretion of chorion. Of the 3 μg in the oocyte, only 1 μg is incorporated into the early embryo while the remainder is found in the yolk cells and serosa.Autoradiography of follicles labeled with H3‐uridine eitherin vivoor by a “pulsechase” procedurein vitroindicated that, as in other polytrophic insect ovaries, the nurse cell nuclei are the most conspicuous source of oocyte RNA. The germinal vesicle incorporated labeled uridine in previtellogenic follicles. In vitellogenic and later stages neither a germinal vesicle nor a follicle cell contribution to oocyte RNA was detected by the proce