nephridium(redirected from Protonephridium)
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Related to Protonephridium: Metanephridium, Protonephridia
n. pl. ne·phrid·i·a (-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.
[nephr(o)- + Latin -idium, diminutive suff. (from Greek -idion).]
n, pl -ia (-ɪə)
(Zoology) a simple excretory organ of many invertebrates, consisting of a tube through which waste products pass to the exterior
[C19: New Latin: little kidney]
ne•phrid•i•um(nəˈfrɪd i əm)
n., pl. -phrid•i•a (-ˈfrɪd i ə)
an excretory tubule in annelids, mollusks, and other invertebrates that discharges wastes from the body cavity through a pore on the body surface.
[1875–80; < Greek nephr(ós) kidney]