pronephros
/prəʊˈnɛfrɒs/(also pronephron) Embryology and Zoology
noun
The most anterior (or superior) and first-developing part of the nephrogenic tissue of vertebrate embryos, which is functional only in the larvae of fishes and amphibians, and persists into adult life only in hagfishes and a few teleosts.
Origin
Late 19th century; earliest use found in Ray Lankester (1847–1929), zoologist. From pro- + ancient Greek νεϕρός kidney. In form pronephron after ancient Greek nouns in -ον. Compare German Urniere, Vorniere, Kopfniere. Compare the parallel formations mesonephros, metanephros.