Purpose: To evaluate the developmental expression of Thy-1 in the retina. Thy-1, the most abundant mammalian neuronal surface glycoprotein, is likely to play a significant role in retinal development. In the mammalian retina, it is found predominantly, if not exclusively, on retinal ganglion cells.
Methods: Rat retinae of various ages were stained immunohistochemically for Thy-1 with 2G12, a monoclonal Thy-1 antibody. Sections were analyzed digitally to quantify bound antibody. Using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), the expression of Thy-1 protein was compared with the levels of mRNA detected.
Results: Thy-1-dependent fluorescence was detected in rat retinae from birth, albeit at low levels. Thy-1 labeling was localized predominantly to the ganglion cell layer. Minimal, fine patterns of linear and reticular fluorescence were noted in the inner nuclear layer. Thy-1 levels reached a maximal level at approximately postnatal day 14. RT-PCR measurements showed a similar time course for the increase in Thy-1 expression.
Conclusions: The Thy-1 antigen is present in the inner retina at birth. Its level increases steadily after birth and peaks during the second week of life. Thy-1 expression is approximately coterminous with synaptogenesis of the inner plexiform layer and may play a role in synaptogenesis of the inner retina or in other developmental milestones in the formation of the visual system.