Dendritic growth of DAPI-accumulating amacrine cells in the retina of the goldfish

The dendritic growth of amacrine cells was studied in the retina of the goldfish. Those cells that accumulated the intraocularly injected fluorescent dye 4,6-diamidino-2-phenylindole (DAPI) were compared in retinal wholemounts from small and large animals. Dendritic arbors were stained by intracellular injections of Lucifer yellow. Based upon their dendritic morphology, two types were identified, radiate and fusiform. The dendritic field areas and the number of dendritic terminals were quantitatively compared for cells in small retinas from young fish and large retinas from old fish in the region of the retina that grows by expansion. For both cell types the dendritic fields were significantly larger in the large retinas. The radiate cells had the same number of dendritic terminals in retinas of both sizes, where the fusiform cells in the large retinas had significantly more dendritic terminals than those in the small retinas. This resulted from the addition of new dendrites to the proximal arbor. These data show that with retinal expansion the pattern of dendritic growth by a amacrine cells is cell-type specific.