NEURAL CONTROL OF CELL-SIZE IN THE CORPORA ALLATA DURING THE REPRODUCTIVE-CYCLE OF THE COCKROACH DIPLOPTERA-PUNCTATA (DICTYOPTERA, BLABERIDAE)

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 punctat a. Ultrastructural observations revealed that growth of CA cells resul ted from synchronous proliferation of cellular machinery required for JH synthesis. Cell growth was suppressed in CA of virgin females, in w hich 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 synchronou s autophagy of cellular organelles. While the mechanism initiating aut ophagy is unclear, it is independent of nervous connections between th e CA and brain. We propose that under normal physiological conditions the quantity of JH synthesized by a corpus allatum is determined large ly by the total amount of cellular machinery available for JH producti on. 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 autophag y (nerve independent). In the course of this study, we have found that individual CA cells from D. punctata, like those from Blattella germa nica, retain their ability to synthesize JH III following enzymatic di ssociation of the CA.