Localization of primary cilia in mouse retina

The primary cilia are considered as "cellular antennae" that sense and interchange information with the extracellular environment. Nearly all mammalian cells have a single primary cilium. In the retina, the outer segment of the photoreceptor is known to be a specialized form of primary cilium, but studies on cilia in other layers of the retina are scarce. In this study, we investigated the expression of primary cilia in the whole thickness of the mouse retina using immunofluorescence with three different ciliary markers: Arl13b, acetylated α-tubulin and adenylyl cyclase III. Our results show positive reactions in the photoreceptor layer, outer plexiform layer and ganglion cell layer, which might suggest the possible presence of primary cilia in these areas, but we could not directly prove the strand-like shape of cilia in those areas. In the outer plexiform layer, all three markers showed intense staining along the neuronal synapses, which suggests that the neuronal processes themselves might share the features of cilia.