Quantitative and electron microscopic studies of sensory ganglion cells of the Sprawling mouse.

The L4-6 sensory root ganglia of young and adult Sprawling (Swl) and normal mice were studied. Cell counts showed a great reduction in the total number of ganglion cells in Swl. Cell degeneration was observed in young Swl animals but not in normal littermates. Most of the remaining ganglion cells showed morphological abnormalities very similar to those seen in chromatolytic neurons-enlarged nucleolus, eccentric nucleus with an infolded nuclear membrane, loss of juxtanuclear Nissl bodies and an increase in neurofilaments, Golgi membranes, autophagic vacuoles, and dense bodies. In contrast to the classical changes of chromatolysis the abnormalities in Swl neurons persisted throughout the lifespan of the animals. Reconstructions from serial sections showed that ganglion cells in Swl were highly irregular in shape.