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Sarcocystis is a genus of protozoa. Species in this genus are parasites, the majority infecting mammals, and some infecting reptiles and birds. The life-cycle of a typical member of this genus involves two host species, a definitive host and an intermediate host. Often the definitive host is a predator and the intermediate host is its prey. The parasite reproduces sexually in the gut of the definitive host, is passed with the feces and ingested by the intermediate host. There it eventually enters muscle tissue. When the intermediate host is eaten by the definitive host, the cycle is completed. The definitive host usually does not show any symptoms of infection, but the intermediate host does. There are about 130 recognized species in this genus. Revision of the taxonomy of the genus is ongoing, and it is possible that all the currently recognised species may in fact be a much smaller number of species that can infect multiple hosts. The name ''Sarcocystis'' is dervived from Greek: ''sarx'' = flesh and ''kystis'' = bladder. ==History== The organism was first recognised in a mouse by Miescher in 1843.〔Miescher F. (1843) Ueber eigenthiimliche Schlauche in den Muskeln einer Hausmaus. Ber. u.d. Verhandl. Naturf. Ges. Basel 5: 198-202〕 His findings were not recognised as a protist initially and the literature referred to the structures he described as "Miescher's Tubules". Incidentally Miescher's son — Johann Friedrich Miescher — discovered DNA. Similar structures were found in pig muscle in 1865 but these remained unnamed until 1899 when the name ''Sarcocystis meischeriana'' was proposed to identify them. Initially it was unclear whether these organisms were fungi or protozoa. This uncertainty was resolved in 1967 when electron microscopic studies showed that these organism were protozoa, related to ''Toxoplasma'' and ''Eimeria''. The life cycle remained unknown until 1970 when bradyzoites from sarcocysts in bird muscles were inoculated into cultured mammalian cells and underwent development into sexual stages and oocysts. Transmission studies with the three morphotypes found in cattle then considered a single species - ''Sarcoplasma fusiformis'' - in dogs, cats and humans revealed that these were three different species now named ''Sarcoplasma bovicanis'', ''Sarcoplasma bovifelis'' and ''Sarcoplasma bovihominis''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sarcocystis」の詳細全文を読む スポンサード リンク
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