Confocal image of an eye-antennal disc from a

third instar Drosophila larva. The red stain shows the presence of a benign cell marker costal2. The green stain shows the presence of the transcription factor Cubitus Interruptus: this is expressed at high levels in a stripe across the eye disc (morphogenetic furrow) and is ectopically up-regulated in cells lacking costal2 function. The right hand panel shows the merging of the red and green channels. The first signs of the adult eye facets can be seen below the furrow. Biomedical Image Awards 1999.