amnion vs pellicle

amnion

noun
  • The innermost membrane of the fetal membranes of reptiles, birds, and mammals; the sac in which the embryo is suspended. 

pellicle

noun
  • A thin plastic membrane used as a beam splitter or protective cover. 

  • A skin or coating of proteins on the surface of meat to be smoked, improving the surface adhesion. 

  • The growth on the surface of a liquid culture. 

  • The skin of a mushroom cap. 

  • A thin skin or film. 

  • The outermost layer of a mushroom, often used only for a surface that is viscid and easily peels off. 

  • Cuticle, the hard protective outer layer of certain life forms. 

  • The photosensitive emulsion of photographic film. 

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