Abstract
1. The release of neurotransmitters, hormones, and enzymes involves exquisitely regulated events which ultimately result in the fusion of the secretory vesicle with the cell's plasma membrane, releasing the vesicle contents into the extracellular space. 2. The biochemical and cellular mechanisms mediating exocytosis have been extensively studied in a model system of primary cultured adrenal chromaffin cells. 3. This paper briefly reviews current understanding, and directions of future studies in exocytosis using this model system.