ABSTRACT
Exocytosis from differentiated cells occurs preferentially at the varicosities with very little release, if any, from the smooth processes or cell body [3]. The absence of exocytotic events at the cell body of the differentiated cells could be the result of changes in surface morphology and in the expression and distribution of ion channels in PC12 cells upon differentiation [3]. The absence of catecholamine release from the smooth processes is most likely due to the fact that vesicles do not appear in these locations. The average vesicular catecholamine content observed for exocytosis at varicosities is 178±9 zmol (107,000 molecules), which is not significantly different from that observed at undifferentiated cells; however, a more narrow distribution is observed for the NGFtreated cells (Figure 19).
