Figure 6

Bipolar cell processes decorated with ribbon synapses intrude into the outer nuclear layer in BBS mutant retinas. P21 retinas from Bbs2^−/−, Bbs7^−/− and their control littermates were probed with anti-PKCα and anti-CtBP2/RIBEYE antibodies to visualize bipolar cells and ribbon synapses. In control retinas, PKCα-positive bipolar cell dendrites appear as nodules that contact photoreceptor ribbon synapses in an organized fashion in the outer plexiform layer. In Bbs2^−/− and Bbs7^−/− retinas, bipolar cell processes decorated with ribbon synapses are sometimes observed extending into the outer nuclear layer. ONL: outer nuclear layer; OPL: outer plexiform layer; INL: inner nuclear layer.