The changing effect of the ovary on rates of juvenile hormone synthesis in Diploptera punctata.

The ovary is necessary for the cycle of juvenile hormone (JH) synthesis by the corpora allata which normally accompanies oocyte development in mated adult Diploptera punctata (B. Stay and S. S. Tobe, Gen. Comp Endocrinol. 34, 276-286, 1978; B. Stay, S. S. Tobe, E. C. Mundall, and S. Rankin, Gen. Comp. Endocrinol. 52, 341-349, 1983). Implanting parts of the ovary into ovariectomized females showed that only the basal oocytes were capable of stimulating an increase in rates of JH synthesis (measured by an in vitro radiochemical assay) within 4 days of implantation; apical oocytes and the oviduct were ineffective. Ovariectomized 2-day-old, mated females were used to test the capacity of ovaries of various developmental stages to stimulate increases in rates of JH synthesis within 24 or 48 hr. Previtellogenic ovaries, with basal oocytes less than 0.8 mm long, and those near the end of vitellogenesis, with basal oocytes greater than 1.5 mm long, did not result in an increase in rates of JH synthesis above Ringer-injected controls. Vitellogenic ovaries within this size range did elicit an increase in rates of JH synthesis. Furthermore the degree of increase was dependent upon the size of the oocytes; the ovaries with largest oocytes showed the greatest capacity to increase rates of JH synthesis.