Board Thread:Naruto Discussions/@comment-26104388-20140919031519/@comment-9782468-20140920225802

If you've ever watched Fullmetal Alchemist, I think it's the same principal of losing part of yourself to the portal.

It's not just physically gone, it's used as a toll for the technique. I think he wouldn't be able to bring it back, it was used up as a toll for Izanagi/Izanami