... of tumor suppressor genes that function in two different cell types of the Drosophila larva: the blood cells, and the undifferentiated epithelial cells of developing imaginai discs. Mutations in the aberrant immune responses (air8) gene lead to overproduction and precocious differentiation of blood cells...

... or a neofluar immersion × 25 objective. Imaginai discs are dissected from mature larvae and transferred immediately to the fixative. After 15 min fixation, the discs are rinsed in phosphate–citrate buffer, transferred to 0·2 ml incubation buffer in a plastic well and enough X-gal powder is added...