[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.
Eventually however the formation of the mesonephros commences, and is followed by the atrophy of the pronephros.
For a long time the pronephros and its duct form the only excretory organs of larval Amphibia.
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.