Board Thread:Theories and Speculation/@comment-24267641-20150816132215/@comment-5936871-20150816172835

Seelentau wrote: Yin Release and Yang Release are no chakra natures, if you mean that. They're applied during the process of creating the chakra itself, whereas chakra natures are applied afterwards.

As for the topic, it could be that Yin Release is used to artificially create the cells that are used to replace the destroyed cells. Tsunade doesn't even have Yin Release, though, she only has it on her page cause she used a genjutsu that one time in that filler ep. But according all other sources, she doesn't even have it. So I doubt that. I mean, based on the description of what Yang Release is and the fact that the Senju/Uzumaki inherited it and we already know what type of abilities they have, coupled with what medical-ninjutsu does. On top of us knowing that the Akimichi Clan's jutsu are Yang Release, and several medical-ninjutsu users all being confirmed to have Yang Release. It only makes sense that medical-ninjutsu falls within the Yang Release category.

Also, just like what was said above. The Manga didn't really mention Yin and Yang Release and go in-depth on what they were and what they did until Part 2. We only got one reference to it when Tayuya used her special jutsu, but that's it.