单词 | miracidium |
释义 | miracidiummi·ra·cid·i·umM5353450 (mîr′ə-sĭd′ē-əm, mī′rə-)miracidium(ˌmaɪrəˈsɪdɪəm)Miracidiummiracidium[‚mī·rə′sid·ē·əm]Miracidiumthe first larva in the development of trematodes, parasitic flatworms. The elongated body is 0.03 to 0.3 mm long and clad in large ciliated cells, which are usually distributed in four to six longitudinal rows. At the anterior of the body open the penetrative glands (a vestige of the intestine that has changed its primary function), whose secretions facilitate implantation of the miracidium in the body of the intermediate host. The organism’s nervous system is represented by the anterior medullary mass of nerve cells. The miracidia of many species have an X-shaped pigmented ocellus in front. The excretory organs are a pair of protonephridia. The body cavity contains germ cells. Miracidia usually emerge from the egg in water, swim for a time, and then implant themselves in the body of an intermediate host (usually a mollusk), where they are transformed into sporocysts. miracidiummiracidium[mi″rah-sid´e-um] (Gr.)mi·ra·cid·i·um, pl.mi·ra·cid·i·a(mī'ră-sid'ē-ŭm, -ă),See also: sporocyst (1). miracidium(mîr′ə-sĭd′ē-əm, mī′rə-)miracidiumThe first-stage larva of a fluke such as Schistosoma species Fasciolopsis or Chlonorchis species. Miracidia are released into water in human excreta and invade particular water snails in which the second-stage larvae (sporocysts) form. These release thousands of cercariae, the form that can pass through the skin to infect humans.miracidium(pl. miracidia) the first larval form of a liver- or blood- FLUKE, which develops from the egg as a flat free-swimming, ciliated larva.Miracidium (plural, miracidia) |
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