Allelic Polymorphyism in Toxoplasma Gondii Implications for Interstrain Mating
The life cycle of Toxoplasma gondii is complex with several alternative subcycles. It can, for example, pass from cat to cat through an oral-faecal route, each time going through a sexual cycle in the intestine of the cat. This subcycle can be considered to begin with excretion of highly stable oocysts in the faeces of an infected cat. Upon maturation, these oocysts will contain two sporocysts, each comprising four sporozoites. Transmission occurs when the mature oocysts are ingested by another cat with release of the sporozoites in the intestine. These invade the intestinal epithelium where they divide intracellularly, ultimately differentiating into either micro- or macro-gametes. Fusion of the two gametes gives rise to the zygote which develops into the immature oocyst. The cycle is completed upon release of these oocysts into the environment. Felidae is the only genus known in which gametogenesis and oocyst production occurs.
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