nephridium(redirected from Metanephridium)
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One of the paired, segmentally arranged excretory tubules of invertebrates such as the annelids.
[G. nephros, kidney, + Mod. L. -idium, dim. suffix, fr. G. -idion]
n. pl. nephrid·ia (-ē-ə)
1. A tubular excretory organ in many invertebrates, such as mollusks and earthworms.
2. The excretory organ of a vertebrate embryo from which the kidney develops.
nephridium(pl. nephridia) a primitive excretory organ present in many invertebrates (e.g. the earthworm) in the form of a tube which opens at one end to the exterior. The other end may open into the COELOM or may terminate in a FLAME CELL.
pl. nephridia [L.]
1. either of the paired excretory organs in each body segment of certain invertebrates, having the inner end of the tubule opening into the coelomic cavity.
2. various excretory structures such as the nephron of the embryo.