The nephron is the functional unit of the kidney that generates urine while eliminating waste and excess chemicals from the bloodstream. Each human kidney contains approximately 1,000,000 nephrons. The kidneys (pronephros) of primitive fish, amphibian larvae, and more advanced vertebrate embryos include the most rudimentary nephrons. The nephrons seen in amphibians’ and most fish’s kidneys (mesonephros), as well as in the late embryonic development of more sophisticated vertebrates, have only somewhat more advanced structure. The most mature nephrons are found in terrestrial animals’ adult kidneys, or metanephros, which include reptiles, birds, and mammals.

Nephron | Definition, Function, Structure, Diagram, & Facts | Britannica

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Nephron, functional unit of the kidney, the structure that actually produces urine in the process of removing waste and excess substances from the blood. There are about 1,000,000 nephrons in each human kidney. Learn more about the structure and function of nephrons in this article.