Loss of Ntn1 disorganizes end buds. The Ntn1+/+ end bud (top) displays normal CDH3 staining of the cap cell layer at the tip of the end bud (delineated by the dashed line). In contrast the Ntn1-/- end bud (bottom) displays a loss of adhesion between the cap and luminal cell layers, with a large space forming under the cap cell layer (delineated by the dashed line). This space fills with dissociated cap cells (arrows show three examples) that either die by apoptosis or migrate inappropriately into the body of the end bud. Original magnification approx. ×300.