nephridium

(redirected from Protonephridium)
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Related to Protonephridium: Metanephridium, Protonephridia

ne·phrid·i·um

, pl.

ne·phrid·i·a

(ne-frid'ē-ŭm, -ă),
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]

nephridium

(nə-frĭd′ē-əm)
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.

ne·phrid′i·al adj.

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.