Localization of neurotensin-like immunoreactive amacrine cells in the larval tiger salamander retina

Summary Light microscopic immunocytochemistry was used to localize the populations of NT-like immunoreactive amacrine cells in the larval tiger salamander retina. Seventy-nine percent of NT-immunostained cells observed in transverse cryo-prepared sections were classified as Type 1 amacrine cells. Another 6% were classified as Type 2 amacrine cells, while 15% of the NT-cells had their cell bodies situated in the ganglion cell layer and were tentatively designated as displaced amacrine cells. Each type of NT-like immunoreactive cell was observed in the central and peripheral retina. NT-immunostained processes were observed to ramify in sublayers 3 and 5 of the inner plexiform layer. An examination of retinal whole mounts revealed that NT-amacrine cells were distributed throughout the center and periphery of the retina at a density of 82 ± 24 cells/ mm². The dendritic fields of NT-immunostained amacrine and displaced amacrine cells were observed to be either symmetrically or asymmetrically distributed about their somas. Symmetrical dendritic fields were generally oval-shaped and ranged in diameter from 250 to 500 m (major axis) by 150 to 250 m (minor axis). Asymmetrical dendritic fields were observed to encompass one-half or less of an imaginary circle surrounding their soma of origin and were orientated in all directions. The processes forming asymmetrical dendritic fields ranged from 75 to 260 m in length. Furthermore, partial overlap was often observed between the dendritic fields of adjacent NT-amacrine cells.