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[proh-nef-ros, -ruh s] /proʊˈnɛf rɒs, -rəs/
noun, plural pronephroi
[proh-nef-roi] /proʊˈnɛf rɔɪ/ (Show IPA),
[proh-nef-ruh] /proʊˈnɛf rə/ (Show IPA).
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
Related forms
[proh-nef-rik] /proʊˈnɛf rɪk/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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British Dictionary definitions for pronephros


noun (pl) -roi (-rɔɪ), -ra (-rə)
the first-formed anterior part of the embryonic kidney in vertebrates, which remains functional in the larvae of the lower vertebrates See also mesonephros, metanephros
Derived Forms
pronephric, adjective
Word Origin
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
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pronephros in Medicine

pronephros pro·neph·ros (prō-něf'rəs, -rŏs')
n. pl. pro·neph·roi (-roi) or pro·neph·ra (-rə)
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.
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