Adrenergic neurons in teleost retina

Summary The adrenergic retinal neurons of perch and trout were studied with the fluorescence microscopical method of Falck and Hillarp. Pilot studies were also performed on pike, plaice, cod, eel, goldfish, cunner, black moor, cichlid and carp. Only minor differences were noted between the species.Adrenergic varicose terminals occur in three sublayers of the inner plexiform layer. The layer adjacent to the ganglion cells is the most elaborate. Adrenergic perikarya occur in the innermost cell rows of the inner nuclear layer, sending branches to all sublayers of the inner plexiform layer. Adrenergic perikarya also occur among the ganglion cells, sending their branches to the innermost sublayer of adrenergic fibres in the inner plexiform layer. Weakly fluorescent adrenergic fibres can be seen running through the entire depth of the inner nuclear layer. They originate from the adrenergic perikarya of the inner nuclear layer, and they end in an elaborate plexus of adrenergic terminals among the horizontal cells. Either of the horizontal cell types can be in contact with adrenergic terminals, but the middle horizontal cells have the greatest density about them, being surrounded by baskets of adrenergic terminals of presumably synaptic character. It cannot be excluded that some horizontal cells contain a catecholamine.Microspectrofluometry revealed dopamine in the perch and trout retinal neurons.The research reported in this document has been sponsored by USPHS Grant No. 06092 and by a Research Professorship from Research to Prevent Blindness, Inc. to A.M.L. and by the Swedish Medical Research Council (B69-14X-712-04C and B68-14X-2321-01).