Confrontation of scabrous expressing and non-expressing cells is essential for normal ommatidial spacing in the XXXX eye.

@entity735 @entity238 @entity71216
The establishment of neural precursor cells in @entity238 depends on cell-cell interactions and lateral inhibition. Scabrous ( @entity71216 ) is involved in this process by preventing an excess of cells from adopting a neural precursor fate. Specifically in eye development, @entity71216 protein function has been implicated in the spacing pattern that is essential for the ordered appearance of the ommatidial array. During this process @entity71216 expression is restricted to neurogenic groups of cells and later to the neural precursors. We report that ectopic @entity71216 expression in the morphogenetic furrow results in a rough eye phenotype with oversized and fused ommatidia. These defects in @entity735 are due to the generation of too many ommatidial preclusters in the morphogenetic furrow. Strikingly, @entity71216 loss-of-function mutants have an almost identical phenotype. Our results suggest that @entity71216 plays a positive role in establishing the spacing pattern within the furrow and that the quantitative difference in @entity71216 expression between neighboring groups of cells is a determining factor in this process. Ectopic expression of @entity71216 also represses endogenous @entity71216 expression in the furrow, suggesting that @entity71216 is involved in a feedback loop affecting its own transcription. Interestingly, @entity71216 shares homology to a group of extracellular matrix proteins that have been implicated in neuronal differentiation. We present a model for @entity71216 function based on its phenotypic and molecular features.
