Morphological identification of amacrine cells in the zebrafish retina

The zebrafish is a powerful vertebrate model in the study of visual neuroscience. Amacrine cells in the zebrafish retina were labeled using the DiOlistic technique, in which a gene gun delivers microcarriers coated with the lipophilic dye DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) onto retinal slices. Incorporation of the dye allows for visualization of somata and dendritic processes. The cells were morphologically classified according to dendritic field widths, dendritic stratification patterns, and/or soma shape. Eighteen amacrine cell types were identified. Four Aoff types were monostratified in s1, one Aoff type was monostratified in s3, and two Aoff types ramified simultaneously in s1/s2 and s1/s3. Dendritic fields were 60-130 mum in both these groups. Six A on types were identified with dendritic processes innervating sublamina b of the IPL. Both rounded and pyriform-shaped somata were seen. Dendritic fields ranged in size from ∼0-110 mum. Of the five bistratified Abi cell types identified, one innervated s1/s4, three innervated s1/s5, and one innervated s2/s5. Dendritic fields were typically 20-140 mum. These results are important in determining the function of each morphological type and how they are affected in visual diseases.