Reversible intracellular displacement of the cytoskeletal protein and organelles by ultracentrifugation of the sympathetic ganglion.
Superior cervical ganglia of rats were centrifuged at 40,000 rpm (160,500 g) for 1 h at 4 degrees C. Most neuronal somata exhibit a minor centripetal domain free of organelles and a major centrifugal domain rich in organelles. The former is occupied by numerous fine granules having low electron density unlike ribosomes in epoxy sections stained with uranium and lead, and is occupied by a meshwork of microtrabecular or filamentous elements similar to that of the centrifugal domain as well as that of the normal cells in PEG (polyethylene glycol)-processed embedment-free sections without staining. The latter centrifugal domain contains regular cell organelles except for neurofilaments without stratification. All the organelles are suspended in the meshwork of microtrabecular or filamentous elements. In immunolight microscopy, NFPs (neurofilament proteins) are confined to the centripetal domain. In immunoelectron microscopy using ultrathin cryosections and the protein A-gold labeling, numerous gold-particles for NFPs were deposited randomly in the centripetal cytoplasmic domain without long linear alignment. In the PEG sections the gold-labelings for NFPs are randomly deposited on portions of the microtrabecular strands in the centripetal domain. After incubation of the centrifuged ganglia in the anterior eye chamber overnight, NFPs-immunoreactivity appears again diffusely throughout the entire cytoplasm of all neuronal somata in immunolight microscopy. The organelle-free domain of the cytoplasm is no longer visible in electron microscopy. The present findings are discussed in relation to the state of the cytoplasmic soluble proteins and the reality of the microtrabecular or filamentous elements in the cytoplasm.