User blog comment:Xilinoc/Ch. 591 - Marching Out the ZOMBIES 2/@comment-24153155-20140730134113/@comment-11051098-20140730161854

Mayuri already stated before that he can remodel/recreate a Zanpakutô if its hilt remains undamaged. Maybe he collected the bodies of the Arrancars who were still whole, to some point, and used the remains to recreate them, even down to their accurate personalities and powers?

Only Tite knows what Mayuri is capable of.