A fluorescent microscopic study of adrenergic innervation of the appendix in rabbits and cats

The authors studied the innervation of the appendix in rabbits and cats. Ad renergic nerve components in rabbits were visualized by glyoxylic acid hist ofluorescence method and in cats by the method of formol-induced fluorescen ce of catecholamines and 5-HT. Adrenergic nerve components enter the appendix in the investigated species "from outside" in a common bundle with arteries and line these vessels in t he form of plexiform bundles of nerve profiles as far as their terminal ram ification in the organ wall. Nerve fibres, supplying both the longitudinal and circular layer of the wall musculature, branch away from the periarteri al plexuses as well as nerve profiles entering the neuropil between neurocy tes of myenteric and submucous plexuses. Moreover, they form loose plexuses of nerve fibres in the lamina muscularis mucosae and penetrate the mucosal glands. In the interdomal regions they finally branch out to loose and irr egular plexuses of very delicate nerve profiles. In both species, the highest density of specifically fluorescent neural com ponents is recorded in the compartmens of submucosa and mucosa, lying out o f aggregated lymphoid follicles, whereas these fibres do not penetrate into the follicles, or B-dependent parts.