Abstract
Abstract: :
Purpose: Because of the ever increasing number of mutants, the mouse retina is becoming a preferred object to study mammalian retinal organization. A detailed classification of bipolar cells of the mouse is still missing, and this was the aim of the present study. Methods: Bipolar cells were intracellularly injected in retinal slices with Lucifer Yellow and Neurobiotin. Bipolar cells were also immunostained with antibodies against calcium binding proteins (CaB1, CaB5, caldendrin, recoverin), neurokinin receptors (NK-3) and the plasma membrane Ca-ATPase1 (PMCA1). Results: Intracellular injections revealed at least 9 types of cone bipolar (CB) cells and one rod bipolar (RB) cell. They were mainly distinguished by the level of stratification of their axons in the inner plexiform layer (IPL). Four CB cells are putative OFF CB cells; five CB cells, amongst them a blue cone selective cell, appear to be ON CB cells. The bipolar cell diversity observed by intracellular staining was corroborated through selective immunocytochemical markers. CaB5 was expressed in an OFF CB cell, an ON CB cell and in RB cells. Antibodies against NK3, CaB1 and caldendrin labeled the same two OFF CB cells. PMCA1 was expressed in an OFF and in an ON CB cell, recoverin in an OFF CB cell. Taken together the immunocytochemical markers distinguished five bipolar cell types. Conclusions: Comparable to primate, cat, rat and rabbit retinae, at least 10 different bipolar cell types are present in the mouse retina. Their axons terminate at different levels of the IPL where they contact different sets of amacrine and ganglion cells.
Keywords: bipolar cells • immunohistochemistry • retina: proximal(bipolar, amacrine, and gangli