Some observations on the fine structure of the sympathetic ganglion of bullfrog.

Electron microscope observations of abdominal sympathetic ganglia of American bullfrogs, Rana catesbiana, have demonstrated the presence of specific areas of cytoplasm in the superficial zone of the perikaryon which are devoid of granulated endoplasmic reticulum. These areas are occupied almost exclusively by granules 200 to 400 A in diameter which can be stained intensely with lead hydroxide but faintly with uranyl acetate. Each granule shows subgranular internal structure after the lead staining. Granules of similar properties are found in synapses also, and may be glycogen. From the satellite cell there extends a number of leaf- or finger-like cytoplasmic projections around the root portion of the nerve process. Some of these projections directly cover the surface of the nerve process. Many others, however, are separated from the neuron by a fairly wide interspace. Multivesicular bodies of the neuron are occasionally observed in a configuration which suggests that they are being extruded from the root of the nerve process into the interspace. Filaments about 100 A in thickness are found in the satellite cell cytoplasm. They are arranged more or less parallel to each other and are especially well developed around synapses and nerve fibers.