Side views of the ferret brain. In each view, right and left correspond to the anterior and posterior sides. In a normal ferret brain, a gyrus extends in a straight manner (arrow head), while in an abnormal ferret brain where FGF signaling is inhibited, a gyrus is discontinued (arrow). This result shows the importance of FGF signaling in gyrus formation. The bright area in the right lower panel indicates the position where FGF signaling is inhibited.