Degeneration of the distal vagal ganglion cells of the domestic fowl after section of their central processes.

The centrally directed axonal processes of the distal vagal ganglion cells were cut by midcervical vagotomy in nine domestic fowl, and the ganglion cells were examined electron microscopically after intervals of 5-462 days. During the first 5-41 days after operation, peripheral displacement of the nucleus, indentation of the nuclear membrane, dilation of the cisternae of the granular endoplasmic reticulum, depletion of membrane associated ribosomes, and peripheral displacement and fragmentation of the Golgi apparatus were found. These changes are interpreted as reactive responses to the axonal injury. From 207 days onwards, general loss of organelles and extensive vacuolation of the cytoplasm were observed. These changes were regarded as severely degenerative, to the point of cell death. Between 305 and 462 days many ganglion cells were lost, the few survivors apparently being normal except for numerous nuclear pores. Degenerative changes were also seen in satellite cells. It is concluded that severance of the central processes of the distal vagal ganglion cells of this avian species leads to the slow development of reactive and degenerative changes in many of the ganglion cells. These results are compared with those of similar experiments on mammals, in which the sensory ganglion cells appear to be totally unresponsive to the interruption of their centrally directed processes.