Board Thread:Naruto Discussions/@comment-1512913-20170417105433/@comment-734582-20170418105057

Elveonora wrote: Um, you are wrong Kill. Danzo did indeed use Wood Release, but it started to take over afterwards and he was forced to cut his arm. He doesn't use it like Yamato does. The tree he grew is more akin to the Zetsu spiralling out of control due to Kurama's chakra. It's not exactly the refined control people are talking about here. Besides we know from the Yamato experiment that Hashi's cells will become plantlife on their own when they spiral out of control, so Danzo's use was more akin to releasing his grip on the cells rather than actual proper wood release like Yamato.

The Zetsu themselves never use wood release, only Spiral Zetsu was able to use it in conjuction with another Wood Release user, either Obito or Yamato. This suggests that while the ability is present in Zetsu, it's in a much weaker form. As far as i can remember, encased by Spiral Zetsu is the only time Obito used wood release.

Because of this, it seems logical to me that Naruto and Sasuke received some of those Zetsu cells, granting them the healing and use of prosthetics without the easy (or rather: Overwhelming) use of wood release.