ovum vs spore

ovum

noun
  • The female gamete in animals; the egg cell. 

spore

noun
  • A reproductive particle, usually a single cell, released by a fungus, alga, or plant that may germinate into another. 

  • A thick resistant particle produced by a bacterium or protist to survive in harsh or unfavorable conditions. 

verb
  • To produce spores. 

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