New aspects of the localization of catecholamines in adrenergic neurons

Publisher Summary This chapter discusses new aspects of the localization of catecholamines in adrenergic neurons. The amine storing sites of adrenergic axons have been reinvestigated with an improved technique for the detection and localization of biogenic amines with the electron microscope. In addition to the well documented large and small dense core vesicles, the axons, especially their terminals, were revealed to contain a distinct third compartment, a tubular reticulum storing amines. On the other hand, the nerve fibers while containing much less amine storing vesicles per surface area compared to their terminals, show a similar proportion of large and small vesicles able to store norepinephrine (NE). Thus, small vesicles storing amines do not only exist in the nerve terminals but also in the whole axon, and presumably in the whole neuron. It is suggested that the three different compartments storing amines are formed in the cell body and probably migrate to the axonal terminals by means of neuroplasmic flow.