[proh-nef-ros, -ruh s]
- one of the three embryonic excretory organs of vertebrates, which becomes the functional kidney of certain primitive fishes.
Origin of pronephros
1875–80; < New Latin < Greek pro- pro-2 + nephrós kidney
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for pronephros
The knob forms the only structure which can be regarded as a rudiment of the pronephros.
For a considerable period the pronephros constitutes the sole functional part of the excretory system.
They are present for a considerable portion of the body cavity, extending backwards from a point shortly behind the pronephros.
For a long time the pronephros and its duct form the only excretory organs of larval Amphibia.
Eventually however the formation of the mesonephros commences, and is followed by the atrophy of the pronephros.
C19: New Latin, from pro- ² + Greek nephros kidney
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
- A kidneylike organ, being either part of the most anterior pair of three pairs of organs in a vertebrate embryo, usually disappearing early in embryonic development.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.