[Ultrastrastructural and histochemical examinations of afferent pathways of the geniculate-cortical relay cells].

On the basis of ultrastructural and ultrahistochemical studies in the dorsal part of lateral geniculate nucleus (d LGN) of albino rat a topistical model of geniculo-cortical relay cell (GCR-cell) afferentiation is proposed. Retinal afferent terminals of type 2a and 2b and their synaptic properties are discussed in connection with slow and fast conducting retinofugal channels. Interneuronal contacts are represented by presynaptic dendritic specializations (P-bouton) and by axonal terminals (F-bouton) (LIEBERMAN and WEBSTER, 1974). These findings suggest that the function of interneurons may be dualistic. Cortical afferents are represented by small terminals with round agranular vesicles. Using the "false" transmitter 5-OH-DA we succeeded in demonstrating degenerating terminals with dense core vesicles. There is evidence that noradrenergic axons originating in the Locus coeruleus may contact with the distal dendritic parts of GCR-neurons.