EXPRESSION OF SONIC-HEDGEHOG AND ITS PUTATIVE ROLE AS A PRECURSOR CELL MITOGEN IN THE DEVELOPING MOUSE RETINA

We show that Sonic hedgehog and patched are expressed in adjacent doma ins in the developing mouse retina. Treatment of cultures of perinatal mouse retinal cells with the amino-terminal fragment of Sonic hedgeho g protein results in an increase in the proportion of cells that incor porate bromodeoxuridine, in total cell numbers, and in rod photorecept ors, amacrine cells and Muller glial cells, suggesting that Sonic hedg ehog promotes the proliferation of retinal precursor cells. These find ing suggest that hedgehog and patched are part of a conserved signalli ng pathway in retinal development in mammals and insects.