The study of secretory vesicle dynamics is a continuing challenge. Classica
lly it was studied using biochemical techniques, such as subcellular fracti
onation and immunoprecipitation, combined with time-consuming electron micr
oscopy studies. The recent development of confocal microscopy, giving in-fo
cus optical section images throughout the thickness of a fluorescently labe
led sample, allows scientists to study the key events in the secretory cycl
e at the level of light microscopy. This study demonstrates the use of spec
ific antibodies against marker proteins of two different secretory vesicles
(synaptic vesicles and large dense-cored vesicles) to follow their exo-end
ocytosis dynamics in peripheral adrenergic neurons. Only in recent years ha
s insight grown regarding the presence of both exocytosis pathways in the s
ame neuron. Confocal microscopy is a suitable technique to study aspects of
exocytosis, endocytosis, and intracellular sorting and as such improves ou
r knowledge on the interaction between both secretory pathways. (C) 1999 Ac
ademic Press.