Abstract
Abstract: :
Purpose: To characterize the different morphological types of horizontal, bipolar, and amacrine cells in the zebrafish retina. This information is important for future studies examining changes in synaptic transmission and function resulting from visual system defects and/or mutations. Methods: Cell types in the INL of the zebrafish retinal slice were morphologically identified using diolistic techniques. In this method, diI-coated microcarriers are applied to retinal slices using a gene gun. Results: Horizontal, bipolar, and amacrine cell types were distinguished based on cell body location and process ramification patterns. Horizontal cell somata, located in the distalmost INL, were used to separate distinct types. Somata were either flattened (n = 3) or rounded in appearance (n = 9), with many short dendritic processes extending to cone pedicles in the OPL. In general, the dendritic tree of all horizontal cell types was not much larger than the diameter of the cell body. Axons were only observed on rounded cells. Bipolar cells were found in the mid to distal INL and separated into 16 different morphological types based on axon terminal ramification patterns. Both monostratified and multistratified cells were observed. Monostratified cells were separated into ON- (n=34) or OFF- (n = 22) cell types based on the depth of terminal puncta in the IPL. Multistratified cells (n = 11) were less frequent and typically had axon terminals located in both the ON-and OFF-sublaminae. Amacrine cell bodies were located at the INL/IPL border and could be divided into at least 7 cell types. Monostratified cells ramifying in sublamina a (n = 16) typically displayed wide dendritic fields; while pyriform cells ramifying in sublamina b (n = 17) had narrower dendritic extent. Multistratified amacrine cells were least abundant (n = 5). Conclusion: Taken together, these data show that the zebrafish retina displays a diversity of second and third order cell types responsible for processing visual information.
Keywords: comparative anatomy • retina: distal(photoreceptors, horizontal cell • retina: proximal(bipolar, amacrine, and gangli