Neural control of cell size in the corpora allata during the reproductive cycle of the cockroach Diploptera punctata (Dictyoptera: Blaberidae)

Abstract

Summary Rising and subsequent falling rates of juvenile hormone (JH) synthesis occurred concurrently with synchronous growth and atrophy of CA cells during the ovarian cycle in mated adult females of Diploptera punctata. Ultrastructural observations revealed that growth of CA cells resulted from synchronous proliferation of cellular machinery required for JH synthesis. Cell growth was suppressed in CA of virgin females, in which rates of JH synthesis remained low, but was stimulated by mating or by severance of nerves leading from the brain to the CA. Atrophy of CA cells during declining rates of JH synthesis was due to synchronous autophagy of cellular organelles. While the mechanism initiating autophagy is unclear, it is independent of nervous connections between the CA and brain. We propose that under normal physiological conditions the quantity of JH synthesized by a corpus allatum is determined largely by the total amount of cellular machinery available for JH production. Therefore, the cycle of JH synthesis in mated adult females of D. punctata is regulated mainly through synchronous proliferation of cell components (under neural inhibition) followed by synchronous autophagy (nerve independent). In the course of this study, we have found that individual CA cells from D. punctata, like those from Blattella germanica, retain their ability to synthesize JH III following enzymatic dissociation of the CA.