The expression of CSAS in Drosophila brain during different developmental stages. A, CSAS expression in the late embryo at stage 17 is detected in the developing CNS, including the ventral ganglion (arrowheads) and brain hemispheres (arrows). Lateral view, Anterior is to the right. B, Third instar larval brain shows a widespread CSAS expression. Arrowheads, Expression in the lateral regions of the ventral ganglion. Arrows, Expression in brain hemispheres. Ventrolateral view, Anterior is to the right. C, CSAS is expressed broadly in the adult brain, including the optic lobes (arrows). Frontal view, Only one optic lobe is shown.