Tachyzoite

Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is typified by a ''cellular variety'' with a distinct morphology and biochemistry.

Not all apicomplexa develop all the following cellular varieties and division methods. This presentation is intended as an outline of a hypothetical generalised apicomplexan organism.

Methods of asexual replication

Apicomplexans (sporozoans) replicate via ways of multiple fission (also known as schizogony). These ways include , and , although the latter is sometimes referred to as schizogony, despite its general meaning.

Merogony is an asexually reproductive process of apicomplexa. After infecting a host cell, a trophozoite ( see glossary below) increases in size while repeatedly replicating its nucleus and other organelles. During this process, the organism is known as a or . Cytokinesis next subdivides the multinucleated schizont into numerous identical daughter cells called merozoites ( see glossary below), which are released into the blood when the host cell ruptures. Organisms whose life cycles rely on this process include '' Theileria'', '' Babesia'', '' Plasmodium'', and '' Toxoplasma gondii.''

Sporogony is a type of sexual and asexual reproduction. It involves karyogamy, the formation of a zygote, which is followed by meiosis and multiple fission. This results in the production of sporozoites.

Other forms of replication include and .
Endodyogeny is a process of asexual reproduction, favoured by parasites such as '' Toxoplasma gondii''. It involves an unusual process in which two daughter cells are produced inside a mother cell, which is then consumed by the offspring prior to their separation.

Endopolygeny is the division into several organisms at once by internal budding.

Glossary of cell types

Infectious stages

A (ancient Greek ', seed + ', animal) is the cell form that infects new hosts. In '' Plasmodium'', for instance, the sporozoites are cells that develop in the mosquito's salivary glands, leave the mosquito during a blood meal, and enter liver cells ( hepatocytes), where they multiply. Cells infected with sporozoites eventually burst, releasing merozoites into the bloodstream. Sporozoites are motile and they move by gliding.

A (G. ', part f a series+', animal) is the result of merogony that takes place within a host cell. During this stage, the parasite infects the host's cells and then replicates its own nucleus and induces cell segmentation in a form of asexual reproduction. In coccidiosis, merozoites form the first phase of the internal life cycle of coccidian. In the case of '' Plasmodium'', merozoites infect red blood cells and then rapidly reproduce asexually. The red blood cell host is destroyed by this process, which releases many new merozoites that go on to find new blood-borne hosts. Merozoites are motile. Before schizogony, the merozoite is also known as the schizozoite.

A ( G. ', partner + ', cell) is a name given to a parasite's gamete-forming cells. A male gametocyte divides to give many flagellated microgamete

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