Intercellular Communication in An Insect Endocrine Gland

1. The parenchymal cells of the corpora allata (CA) of the cockroach Diploptera punctata are coupled through low-resistance intercellular pathways. 2. Extensive dye coupling of cells of CA from fourth instar and adult female cockroaches was revealed following iontophoretic injection of Lucifer Yellow. 3. Freeze-etch electron microscopy revealed numerous gap-junction-like particles in CA cell plasma membranes. 4. The spread of ionic current from cell to cell was demonstrated by injecting current pulses into one cell and recording electrotonic potentials from other cells. The amplitude of electrotonic potentials elicited by negative current injection varied inversely with the rate of juvenile hormone biosynthesis by the CA. 5. The ‘length constant‘ (distance at which an electrotonic potential in CA cells decays to 37% of its magnitude at the site of current injection) could not be measured accurately, but was found to be much greater than the length of the CA. 6. Forskolin- and IBMX-induced elevation of intracellular cAMP increased the electrotonic potential but reduced juvenile hormone release of day 8 CA.