Changes in Thy-1 antigen immunoreactivity in the rat retina during pre- and postnatal development.

Although Thy-1 is one of the most abundant surface glycoproteins in mammalian central neurons, its functional role is still not clarified. In this study we demonstrate that Thy-1 expression in the rat retina starts only at embryonic day 19 on both the cell somas and processes of retinal ganglion cells. Thy-1 immunoreactivity in the ganglion cell layer increases until postnatal day 14 and is paralleled by an increase in the thickness of the inner plexiform layer. Thus, the beginning of Thy-1 expression is correlated with a developmental stage when axonal elongation and neurite sprouting of ganglion cells has finished and refinement of synaptic structures in the colliculus superior begins. From postnatal day 9 on, Thy-1 immunoreactivity can also be observed on cell somas at the border of the inner plexiform/inner nuclear layer.