External adrenergic innervation of the three neuron types of Dogiel in the plexus myentericus and the plexus submucosus externus of the porcine small intestine.

For the simultaneous demonstration of intramural enteric ganglion cells and the adrenergic nerve fibres in the porcine small intestine a combined histochemical method was developed using a hypertonic solution, the main chemicals of which were glyoxylic acid, Nitro-BT and NADH. By means of the enzymatic histochemical method reaction for the NADH-dependent dehydrogenase activity with Nitro-BT as an electron acceptor, the identification of the three neuron types of Dogiel (i.e. type I, type II, type III) was for the first time realized in relation with the glyoxylic acid induced fluorescence (GIF) of the plexus myentericus (Auerbach) and the plexus submucosus externus (Schabadasch). Besides the close topographic relationship between the adrenergic varicose axons on the one hand and the perikarya and dendrites of the multidendritic uniaxonal type I cells characterized by radially oriented short and lamellar dendrites and the multidendritic uniaxonal type III cells, characterized by radially oriented long and tapering dendrites on the other hand, it is striking that for the adendritic multiaxonal type II cells the fluorescent varicose fibres adhere closer to the cell bodies and their processes. In principle, the relation between adrenergic varicose axons and neuron types is identical in plexus myentericus (Auerbach) and plexus submucosus externus (Schabadasch), yet with the exception that in the latter no type I neurons are observed.