Studies on the Neurosecretory Control of Egg Laying inAplysia

Studies are reviewed on the electrophysiological and endocrinological features of a group of neurosecretory cells (the big cells) in the abdominal ganglion of Aplysia. Electrophysiological studies suggest that the bag cells are involved in the regulation of a phasic behavioral function such as egg laying. Egg laying occurs approximately one hour following the injection into the hemocele of a crude extract of the bag cells or of the perfusate of an abdominal ganglion in which a pleural abdominal connective is electrically stimulated. The bag cells appear to act as a unit, releasing a measured dose of egg laying hormone when they are triggered into activity.