Zool. a primitive kidney, the most anterior of three pairs of renal organs, functional only during embryonic development in most lower vertebrates, and appearing only transiently in the human embryo
Origin of pronephrosModern Latin from pro-, pro- + Classical Greek nephros, kidney: see nephro-
nounpl. pro·neph·roi, or pro·neph·ra
A kidneylike organ, being either part of the most anterior pair of three pairs of organs in a vertebrate embryo, disappearing early in the embryonic development of most vertebrates.
Origin of pronephrospro- 2Greek nephros kidney