Abstract
Abstract: :
Purpose: Recent work revealed that light deprivation alters the developmental changes of light evoked synaptic inputs from ON and OFF pathways of mouse retinal ganglion cells (RGCs). This was proposed due to the activity-dependent pruning of RGC dendrites. In this study, I examined the patterns of RGC dendritic ramification of mice reared under normal cyclic light conditions and constant darkness from birth. Methods: Mouse RGCs are visualized by expressing YFP in a subgroup of Thy1 positive cells. The 3-dimensional images of YFP positive RGCs are captured from normal reared mice at the ages of P10 and P30 and dark reared mice at P30 using a confocal microscope. The structural properties are further analyzed using software Neurolucida. Results: (1) All types of the previously identified mouse RGCs are found in Thy-1 YFP positive cells in mouse retina. (2) RGC dendritic ramification patterns undergo a developmental change in normally reared mice after eye opening. At the age of P10, 53 ± 2.7% of YFP positive RGCs are bistratified cells and 47% of them are monostratified, in which 43 ± 2.3% of them ramify in sublamina b and 4 ± 2.3% of them ramify in sublamina a. At the age of P30, only 28 ± 2.8% of RGCs are bistratified, 41 ± 2.4% of cells are monostratified in sublamina b and 30 ± 3.3% of cells are monostratified in sublamina a. (3) Light deprivation blocks the age-related changes of RGC dendritic ramification. In mice reared in constant darkness from birth to P30, 54 ± 2.8% of YFP positive RGCs are bistratified, 33 ± 2.4% of cells only ramify in sublamina b and 13 ± 0.9% of cells only ramify in sublamina a. Conclusions: Thy1-YFP transgenic mouse serves as a good model for the study of mouse RGC morphology. Mouse RGCs undergo structural refinement in postnatal development after eye opening. This developmental refinement is visual activity-dependent.
Keywords: ganglion cells • retinal connections, networks, circuitry • plasticity