Abstract
The spinal cord and intestine of the lamprey (Lampetra japonica) were examined with regard to the occurrence f monoaminergic nerve elements by using the Falck-Hillarp method.
1. In the spinal cord fluorescent neurons were found near the central canal along the whole length of the cord. Their axons seemed to run chiefly to the ventral side.
2. A pair of fluorescent areas showing fluorescent spots which presumably corresponded to the cut surfaces of the axons or endings of the fluorescent neurons were seen near the ventral surface of the cord.
3. The axons of the fluorescent neurons were supposed to form the fluorescent areas.
4. Neural elements in the wall of the intestine, in the blood vessels to the intestine of the caudal part and in the cloacal sympathetic ganglion (a tentative name for the ganglion present dorsally to the ureter and intestine of the cloacal region) were, as in the case of the intramedullary fluorescent neurons, assumed to be monoaminergic by referring to the simple specificity test for monoamine fluorescence.
5. It is unknown whether the fluorescent neurons in the spinal cord are the source of the fluorescent fibers in the spinal nerves, both in dorsal and ventral roots.
6. The significance of the fluorescent neural elements found in this examination were discussed with reference to the ontogeny and phylogeny of the commissural sympathetic chain and the enteric plexus.
