They say levels of a protein called Shh need to remain largely unchanged in a developing fetus for the palate to develop correctly.

VOA: special.2009.12.22

And when a compound is decomposed, the atoms are recovered unchanged.

当一个化合物被分解的时候，原子有恢复原来未曾改变的面貌。

麻省理工公开课 - 固态化学导论课程节选