Figure 2. DR6 regulates axon pruning in vitro and in vivo.

(a)Diagram of Campenot chamber (adapted from ref. (24)).

(b)Local degeneration of sensory axons (TuJ1 immunostain) in Campenot chambers after NGF deprivation from the axonal compartment (top) was delayed by anti-DR6.1 (50 ug/ml) added at time of deprivation (bottom). Right: percent degenerating bundles at 24 and 48hr.

(c–j) Compromised pruning of retinal axons in DR6 −/− mice. Dorsal view of (c, e), and vibratome sections through (d, f), the superior colliculus (SC) of wt (c, d) or DR6 −/− (e, f) mice at P6. (c, d) In wild-type, diI-labeled temporal retinal ganglion cell (RGC) axons form a dense termination zone (TZ) in anterior SC (arrowheads: anterior border). Few are outside the immediate TZ area (arrows), (e, f) In DR6 −/− mice, temporal RGC axons and arbors are present in areas far from the TZ (inset, magnified in (e′)) and well posterior to it (arrows). P: posterior; L, lateral; M, medial.

Scale bar: (b): 200 μm; 400 μm (c, e); 170 μm (e′); 250 μm (d, f).