Fig. 3. p75^NTR and caspases are involved in NGF-induced cell death in the otic vesicle. Apoptotic cell death was visualised by TUNEL. Otic vesicles were isolated from HH18 chicken embryos, made quiescent and cultured for a further period of 8 hours in serum-free medium (A, Control) or 4 nM NGF (B) alone or in combination with 2 µg/ml anti-NGF antibody (C), (1:100) 9651 anti p75^NTR antibody (D) or caspase inhibitors, 25 µM zVAD (F) and 75 µM DEVD (H), as indicated in the panels. Explants were pre-treated for 30 minutes with the antibodies or caspase inhibitors. All the otic vesicles have the same orientation: D (dorsal); A (anterior); cvg (cochleovestibular ganglion). Compiled projections of the whole otic vesicle are shown. Representative microphotographs of three independent experiments using five otic vesicles by condition are shown. Bar, 100 µm.