ANASTOMOSING ADRENERGIC NERVES FROM SYMPATHETIC TRUNK TO VAGUS AT CERVICAL LEVEL IN CAT

The origin, course, and relative contribution of postganglionic sympathetic nerves was investigated in the cervical vagus and in the sympathetic trunk of the cat by the direct fluorescence microscopic demonstration of the adrenergic transmitter. In order to allow a better tracing of the axons, the level of norepinephrine in the preterminal portion was increased through axotomy at a level about 4 cm below the nodose ganglion. Numerous adrenergic fibres were found in the cervical vagus proper. They seemed to arise in the superior cervical ganglion, from which they partly passed in an anastomotic fashion through the adjacent nodose ganglion and partly entered the vagus trunk below this ganglion. Besides preterminal postganglionic sympathetic nerves passing through the ganglion, a few adrenergic terminals of probably vascular nature were also seen to run among the ganglion cells. Also the cervical sympathetic trunk contained postganglionic sympathetic fibres which seem to originate from ganglion cells present in the most caudal pole of the superior cervical ganglion and/or from scattered ganglion cells located below this ganglion. At least part of the adrenergic fibres presently demonstrated in the vagus and in the sympathetic trunk terminate in the heart: superior cervical ganglionectomy produced a significant decrease, 22-27%, in cardiac norepinephrine. © 1969.