Fig. 7. Ommatidial development in the presence and absence of Dmkp3. (A) Schematic representation of the emergence of preclusters in successive rows posterior to the morphogenetic furrow (at row 0). Starting from a `rosette' and `arch' stage (rows 0 and 1), the preclusters in row 3 contain initially equivalent R3/R4 precursors and 1-2 intervening mystery cells (M). The R3/R4 equivalence group is able to sense a graded Frizzled signal from the equator such that the cell closer to the equator becomes R3, the other R4. Subsequently, the preclusters undergo a rotation and thereby achieve chirality. Ultimately, R3 and R4 adopt asymmetrical positions in the ommatidium conveying the typical trapezoidal shape (right, symbolizing the arrangement of rhabdomeres). (B) Between row 3 and row 4 the mystery cell is expelled from preclusters like a melon-seed. We propose that in the absence of DMKP3 function cells from the surrounding pool and also R3 and R4 display altered adhesive properties, thereby affecting the exit of the mystery cell(s) from the precluster.

Return to article