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The egg is found in the faeces, sputum, or urine of the definitive host. Depending on the species, it will either be non-embryonated (immature) or embryonated (ready to hatch). The eggs of all trematodes (except schistosomes) are operculated. Some eggs are eaten by the intermediate host (snail) or they are hatched in their habitat (water).
The trematode Hirudinella ventricosa releases eggs in strings. Each egg contains a single miracidium, while the string contains living spermatozoa . Miracidia have cilia that are only present in the upper portion of the body near an apical gland with 12 hook-like spines in the opening.
Schistosoma is a genus of trematodes, commonly known as blood flukes.They are parasitic flatworms responsible for a highly significant group of infections in humans termed schistosomiasis, which is considered by the World Health Organization to be the second-most socioeconomically devastating parasitic disease (after malaria), infecting millions worldwide.
Egg of S. haematobium. Note the pointed spine on the left tip. Normal infection of adults does not produce symptoms. When eggs are released, they sometimes become permanently stuck in the bladder and cause pathological symptoms. The eggs are initially deposited in the muscularis propria which leads to
The eggs, which are oval, operculated, and light brown, are released from adult Alaria and excreted from the final host's faeces and hatched into miracidium that infect the snail host, in which the eggs then give rise to the asexual stage known as sporocysts. The sporocysts then produce cercariae.
An egg-making organ, the vitelline gland, does not develop in females in the absence of a male. [16] Male gametes, spermatozoa, are present in the oviduct. [17] In males, there are rudimentary ovaries, oviduct, and oocytes (developing female gametes), [18] as well as vitelline cells. [19] Males also possess the genes for hermaphroditism in ...
The eggs of some digeneans, for example, are (passively) eaten by snails (or, rarely, by an annelid worm), [2] in which they proceed to hatch. Alternatively, eggs may hatch in water to release an actively swimming, ciliated larva, the miracidium , which must locate and penetrate the body wall of the snail host.
Schistosoma japonicum is an important parasite and one of the major infectious agents of schistosomiasis.This parasite has a very wide host range, infecting at least 31 species of wild mammals, including nine carnivores, 16 rodents, one primate (human), two insectivores and three artiodactyls and therefore it can be considered a true zoonosis.