AbstractChromaffin cells were studied by fluorescence microscopy in long‐term cell cultures of dissociated chick embryo sympathetic ganglia. These cells were distinguishable in culture from the sympathetic ganglionic neurons by their small size, relative infrequency of occurrence, intense fluorescence and survival in the absence of nerve growth factor (NGF). By several weeks in culture, with or without NGF in the medium, the chromaffin cells produced extensive ramifications of fluorescent varicose processes. It is suggested that at least part of the intraganglionic system of adrenergic varicose terminals arises from chromaffin cells. This capability with regard to fiber production lends credence to the suggestion that chromaffin cells may play an active role in ganglionic functio