DIRECT PROJECTIONS FROM THE SPINAL-CORD TO THE TRIGEMINAL SYMPATHETIC-GANGLION OF THE PUFFER FISH, TAKIFUGU NIPHOBLES

The sympathetic trunk of teleosts extends into the cranial levels, for ming the cranial sympathetic ganglia. When horseradish peroxidase was applied to the trigeminal sympathetic ganglion (a sympathetic ganglion at the level of the trigeminal nerve) of the puffer fish, Takifugu ni phobles, retrogradely labeled neurons were found in the central autono mic nucleus (a distinct cell column in the rostral part of the spinal cord). The central autonomic nucleus has been known to contain pregang lionic neurons projecting to the sympathetic ganglia at the spinal lev els. Thus, the present results indicate that the central autonomic nuc leus in the spinal cord of teleosts contains not only preganglionic ne urons projecting to the sympathetic ganglia at the spinal levels, but also neurons projecting to the sympathetic ganglia at the cranial leve ls.