Demonstration of retinal cells expressing messenger RNAs of the c-kit receptor and its ligand.

We found cells expressing c-kit receptor and its ligand (Sl factor, SLF) in the retina of rats and mice. c-kit messenger RNA (mRNA) was detected in a limited number of cells in the inner nuclear layer of rats and mice by in situ hybridization. The c-kit-expressing cells were assumed to be a subpopulation of the amacrine cells on the basis of their size and distribution pattern. c-kit protein-containing cells were demonstrated in the mouse retina by using ACK2 monoclonal antibody against the extracellular domain of the mouse c-kit receptor. The c-kit protein was detected in cell bodies and processes of the presumed amacrine cells. Hybridization signals for SLF mRNA were observed in the retinal ganglion cells. The results suggest that the c-kit receptor and its ligand may play some roles in the formation of junctions between the amacrine and retinal ganglion cells.