derma vs exoderm

derma

noun
  • The inner layer of the skin. 

  • A Jewish dish of roast or boiled seasoned meat and flour etc. in a casing, especially kishke. 

exoderm

noun
  • An outer layer of skin. 

  • The outermost layer of cells in a developing embryo. 

How often have the words derma and exoderm occurred in a corpus of books? (source: Google Ngram Viewer )