pronephron

pro- +‎ nephron

pronephron (plural pronephrons)

1. (biology) The first part of the urogenital system to be differentiated in a vertebrate embryo, which functions as a simple excretory organ in simpler forms, serves as a provisional kidney in some fish and amphibians, and only appears as a temporary embryonic structure in reptiles, birds, and mammals.
   • 1975, Acta Embryologiae Experimentalis, page 110:

     In addition, while in the pronephron only vacuolization was noted, the structure of the liver had an atypical appearance and there was a considerable number of erythrocytes scattered among the hepatic chords which themselves were noticeably altered.

   • 1982, T. Lenoir, The Strategy of Life, →ISBN, page 106:

     The whole problem turned around a detailed understanding of the so-called Wolffian body, what modern textbooks in embryology designate as the pronephron and its associated Wolffian or pronephric ducts.

   • 1985, Martha Ann Auvenshine & ‎Martha Gunther Enriquez, Maternity nursing: dimensions of change, page 135:

     Regression of the first clusters occurs before the total number of pronephron structures is established. The pronephrons induce the development of the mesonephrons. As the pronephrons regress, the mesonephrons appear.

• pronephros