Abstract
Egg-laying hormone in Aplysia californica is synthesized and secreted by cells that seem to be homogeneous ultrastructurally and electrophysiologically. Several conventional methods have been used to demonstrate histochemical homogeneity and special staining techniques based on the known properties of the hormone show the neuroendocrine organ to be uniform in appearance. Furthermore, since stain specificity for egg-laying hormone is demonstrable using release and biochemical studies, the authors concluded that the organ consists of a population of biochemically homogeneous neurons.