Calretinin in the mouse superior colliculus originates from retinal ganglion cells

We investigated the origin of the calretinin-immunoreactive fibers in the mouse superior colliculus. The dense plexus of calretinin-positive fibers in the superficial layers of the colliculus was completely eliminated after eye enucleation. Retrograde tracing combined with immunohistochemistry revealed many calretinin-positive small-to-medium retinal ganglion cells projecting to the colliculus. These results indicate that calretinin-containing ganglion cells are the source of this calcium-binding protein in the superficial layers of the superior colliculus.