- The ciliated first-stage larva of a trematode that emerges from the egg and must penetrate into the tissues of an appropriate intermediate host snail if it is to continue its life cycle; followed by development into a mother sporocyst and by production of a number of offspring of successive larval generations. SEE ALSO: sporocyst (1). [G. meirakidion, boy]
* * *mi·ra·cid·i·um .mir-ə-'sid-ē-əm, .mī-rə- n, pl -cid·ia -ē-ə the free-swimming ciliated first larva of a digenetic trematode that seeks out and penetrates a suitable snail intermediate host in which it develops into a sporocystmi·ra·cid·i·al -ē-əl adj
* * *n. (pl. miracidia)the first-stage larva of a parasitic fluke. Miracidia hatch from eggs released into water with the host's excreta. They have cilium and swim about until they reach a snail. The miracidia then bore into the snail's soft tissues and there continue their development as sporocyst.
* * *mi·ra·cid·i·um (mi-rə-sidґe-əm) pl. miraciґdia [Gr. meirakidion boy, young man] the first stage larva of a trematode which undergoes further development in the body of a snail.
Medical dictionary. 2011.