R7 cell development in ttk- mutant ommatidia is dependent upon Lz function. A. Projected confocal image of Runt labelled cells in a wild-type disc show one R8 cell per ommatidial cluster for approximately six rows posterior to the morphogenetic furrow (Mf; arrow). At row seven, Runt-expressing R7 cells are recruited to each ommatidium and Runt "doublets" are observed. B. In the ttk1e11 mutant ommatidia, ectopic Runt positive R7 cells are observed. C. Only single R8 cells are observed in developing ommatidia of lzmr1; ttk1e11 ommatidia. B and C show discs where ttk- clones occupied the majority of the eye disc (β-galactosidase not shown). B and C (insets) show mosaic images, where ectopic Runt positive cells can be observed in ttk1e11 clonal patches (B inset; GFP negative clones outlined). C Inset. In lzmr1 mutant discs, R7 cells are not recruited to the ommatidia, and the generation of ttk1e11 clones in this background (outlined in inset) does not result in the recruitment of R7 precursor cells. Scale bars indicate 10 μm.
Siddall et al. BMC Developmental Biology 2009 9:64 doi:10.1186/1471-213X-9-64