mesentery vs pleura

mesentery

noun
  • The membrane that attaches the intestines to the wall of the abdomen, maintaining their position in the abdominal cavity, and supplying them with blood vessels, nerves, and lymphatics. 

pleura

noun
  • Each of a pair of smooth serous membranes which line the thorax and envelop the lungs in humans and other mammals. 

  • A lateral part in an animal body or structure. 

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