Neuropeptide Y-like immunoreactive amacrine cells in the retina of Bufo marinus.

Neuropeptide Y-like immunoreactive (NPY-LI) amacrine cells of the Bufo marinus retina were morphologically characterized, and their retinal distribution was established using immunohistochemistry on retinal wholemount preparations and sectioned material. The somas of NPY-LI amacrine cells were situated in the innermost part of the inner nuclear layer and their dendrites branched primarily in the scleral sublamina of the inner plexiform layer. A subgroup of the NPY-LI cells had dendrites in both the scleral and vitreal sublamina. All immunoreactive cells had large dendritic fields (average 0.5 mm2) that resulted in a high dendritic overlap across the retina. NPY-LI amacrine cells were evenly distributed across the retina, with an average density of 30 cells/mm2, although higher densities were observed at regions adjacent to the ciliary margin. The dendritic field size of the NPY-LI cells, together with the previously characterized substance P-like immunoreactive (SP-LI) amacrine cells, indicates that they belong to the class of wide-field amacrine cells. However, unlike the SP-LI neurons whose dendrites branch in the vitreal sublamina of the inner plexiform layer, the dendrites of the majority of the NPY-LI neurons branch in the scleral sublamina.