Figure 4. Eyespot determination precedes Dll focal expression.

(a) Dll expression in line patterns in a mid-last instar V. cardui forewing imaginal disc. The red box highlights the area of the wing shown in subsequent panels. (b) Eyespot markers Notch and spalt are expressed in foci at a time point when Dll is only expressed in a line extending from the eyespot focus to the wing margin. (c) A time series of Dll expression shows the progression of line, to line-plus-focus (corresponding to b), to focus only.