During metamorphosis, the epithelium of the PC is rearranged into the adult 'air nose', while a new olfactory epithelium, the adult 'water nose', forms in the emerging middle cavity (MC). We quantified cell death in all olfactory epithelia and found massive cell death in the PC and the VNO suggesting that the majority of larval sensory neurons is replaced during metamorphosis in both sensory epithelia. The moderate cell death in the MC shows that during the formation of this epithelium some cells are sorted out. Our results show that during MC formation some supporting cells, but not sensory neurons, are relocated from the PC to the MC and that they are eventually eliminated during metamorphosis. Together our findings illustrate the structural and cellular changes of the Xenopus olfactory organ during metamorphosis.