Abstract
Bipolar cells are responsible of transmitting light signals from photoreceptors to ganglion cells in vertebrate retinas. Their maturation process is not only important for establishing normal visual functions, but may also underlie the dendritic remodeling of ganglion cells during development. It has been shown that light deprivation affects synaptic connections of ganglion cells in the mammalian retina, but little is known about impacts of visual deprivation on bipolar cell development. Here we have used dye injection and gene gun labeling to identify and follow their differentiation in both normal and dark reared rabbits. Our results show that immature bipolar cells can be found as early as P1-3, and most characteristic bipolar cells can be identified in P4-6 of the rabbit retina. Most importantly, we found that light deprivation causes a delay rather than a permanent arrest of the bipolar cell maturation. By eye opening at P10-11, both normal and dark reared rabbits have possessed adult-like bipolar cells. The results suggest that visual experience has a facilitating effect on morphological differentiation of bipolar cells, and early mature bipolar cells could provide light dependent signals to guide synaptic connections of ganglion cells in the inner retina.