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Meaning of pronephros

pro•neph•ros

Pronunciation: (prō-nef'ros, -rus), [key]
— pl. -roi -ra
  1. one of the three embryonic excretory organs of vertebrates, which becomes the functional kidney of certain primitive fishes. Cf.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.