[The catecholaminergic connections of the visual system of the albino rat (author's transl)]

By using the glyoxylic acid method of DE LA Torre and Surgeon (1976), occurrence, distribution and origin of catecholamines were investigated in the visual system of the albino rat. A dense network of green fluorescent terminals and preterminals could be detected in the dLGN. The spreading of terminals of catecholaminergic fibres had been observed in laminae I and II of the visual cortex. Investigation of lamina I with the Golgi-Kopsch method showed axons the thickness of which was below 1 micron, and with varicosities with a distance of approximately 3.5 micron, having a diameter of 2 to 4 micron. These axons might be identical with the fluorescent-histochemically represented terminals. Taking into account the course of catecholaminergic axons it can be concluded that the pyramidal cells of the neocortex, the spiny dendrites of which are heavily branched in the lamina I, are affected. After application of horseradish-peroxidase in the dLGN labelled cells have been found in the locus coeruleus (A6) only. After application of the enzyme in the visual cortex, labelled cells have been observed in the nuclei A 6 and A2. The pathway of catecholaminergic axons from the nucleus of origin to the terminal regions was investigated using the "false transmitter" 6-OH-DA. The results can be seen in a diagram.