REINVESTIGATION OF THE CONTRIBUTION OF THE SUPERIOR CERVICAL-GANGLION TO INNERVATION OF THE RAT THYMUS

In this study the contribution of the superior cervical ganglion (SCG) to the thymic sympathetic nerve supply has been re-investigated. For this purpose, two weeks after the removal of both SCG, the thymic concentrations of noradrenaline (NA) and 5-hydroxytryptamine (5-HT) were measured neurochemically, while the distribution and density of monoaminergic nerve fibers were assessed using the method of fluorescence histochemistry. The activity of acetyl-cholinesterase (AChE), the occurrence of which is well documented in the sympathetic nerves, was also determined neurochemically, and histochemically. The removal of SCG did not significantly affect either the thymic concentrations of NA or intrathymic distribution and density of the autofluorescent fibers, The concentration of 5-HT, as well as the density of autofluorescent cells (afc), also did not differ significantly between the experimental and control rats. The removal of SCG influenced neither the density and distribution of AChE positive fibers nor the intrathymic AChE activity. Thus the results indicate that the neural influence from the SCG on the thymus is either nonexistent or minimal.