Ovarian stimulation of juvenile hormone biosynthesis in the viviparous cockroach, Diploptera punctata.

A direct radiochemical assay for juvenile hormone (JH) biosynthesis by the corpora allata (CA) showed that the cyclic changes in biosynthesis associated with the gonadotrophic cycle were abolished in the absence of ovaries whether or not the CA were innervated. In ovariectomized animals denervated CA synthesized JH at slightly higher rates than did innervated CA. However, the low rates of JH synthesis in ovariectomized females were sufficient to result in accumulation of vitellogenin in the hemolymph to levels twice those of normal females. Implantation of one ovary 1 week after ovariectomy resulted in a cycle of JH biosynthesis qualitatively similar to that observed during a normal gonadotrophic cycle. Implantation of one ovariole did not result in a detectable cycle of JH biosynthesis whereas normal rates of JH synthesis were observed after implantation of three to six ovarioles. Implantation of four ovaries resulted in a cycle of CA activity more attenuated than that observed in the presence of one ovary. Nonetheless all four ovaries sequestered a normal quantity of vitellin.