Metanephros(redirected from metanephra)
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a paired excretory organ in reptiles, birds, mammals, and man that replaces the mesonephros in the course of embryonic development.
The uriniferous tubules of the metanephros form from the nonsegmented posterior part of the nephrotome; unlike the uriniferous tubules of the mesonephros, they begin at the malpighian corpuscles. The ends of the tubules of the metanephros open not into the wolffian duct, as in the mesonephros, but into the ureter, an outgrowth of it.