Secretory organelles in the crayfish nervous system

Abstract 1. 1. Eleven categories of secretory organelles are present in the central nervous system of crayfish: oval clear vesicles, five classes of round clear vesicles, vesicles with a small spot, three classes of dense cored vesicles, and large granules. 2. 2. Clear vesicles are associated to synaptic active zones or electrotonic junctions. Small spot vesicles seem specific of lateral giant axons. Dense cored vesicles are ubiquitous. 3. 3. Small clear vesicles release their content at synaptic active zones. Dense cored vesicles are associated to non-synaptic release. But exocytotic release from large clear and small spot vesicles has not been observed.