Difference between revisions of "Coccidia Life Cycle"

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[[Image:Coccidia_logo.jpg|thumb|right|150px|''Coccidia'' <br> Joel Mills, WikiMedia Commons]]
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[[Image:Coccidia.jpg|thumb|right|150px|Coccidia - Joel Mills]]
  
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Coccidia belong to the phylum Apicomplexa and are [[:Category:Protozoa|protozoan parasites]] of mammals, birds and reptiles. Coccidia have three major stages to their life cycle: Sporogony, Schizogony, Gametogony. The first two stages are asexual, with sexual reproduction occurring in the third stage. The following is a general life cycle though there is some variation in the various suborders.
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Coccidia have three major stages to their life cycle: Sporogony, Schizogony, Gametogony. The first two stages are asexual, with sexual reproduction occurring in the third stage.
  
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===Sporogony/Sporulation===
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===Sporogony===
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Thick shelled '''oocysts''' are passed unsporulated in the feaces of the host, these consist of a single nucleus in a large pool of protoplasm. Sporulation occurs when conditions in the environment are suitable; high humidity, good oxygenation, and temperatures around 27<sup>0</sup>C. The nucleus will divide a number of times depending on the species of coccidia and the number of '''sporocysts''' it will form also depends on the species. After division of the nucleus the protoplasm will form '''conical bodies''' around each nucleus budding off from the central core. The nucleus and conical body together will then form a '''sporoblast'''. The sporoblast will creates a wall for itself by secreting materials, at the same time the protoplasm forms two '''sporozoites''' within the sporocyst wall.  This process can take between 2 and 4 hours under optimal conditions but may take considerably longer if conditions are not suitable.
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This is the fist stage of the coccidia life cycle and occurs exogenously in the environment. Sporozoites develop within the oocyst before it becomes infective. Once the sporozoites have been formed the oocyst is infective and on ingestion by the host will release sporozoites to invade intestinal epithelium.
  
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===Merogony/Schizogony===
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===Schizogony===
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Once the sporozoites have been formed, the oocyst is an infective '''sporulated oocyst''' that is ingested by the host for the life cycle to continue. The remaining stages of the life cycle occur endogenously within the host. The ingested sporozoites are released from the oocyst and activated by trypsin or bile before invading intestinal epithelial cells. When the sporozoites have invaded an epithelial cell they become rounded and are called '''trophozoites'''. This trophozoite will then divide into a number of elongated nucleated '''merozoites''', collectively known as a '''meront'''. Once the meront has grown and matured sufficiently it ruptures along with the epithelial cell, freeing the merozoites to either infect another epithelial cell and repeat the progress or progress on to sexual reproduction.
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Sporozoites grow within intestinal epithelial cells  
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**Sporozoites feed and grow
  
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===Gametogony===
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*As the sporozoite grows the nucleus divides forming a '''schizont'''
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The released merozoites then infect new intestinal cells and differentiate into '''gametocytes'''. The females, known as '''macrogametocytes''' are large single nuclear cells, they increase in size to fill the host cell. Merozoites that develop into the male gametocyte, or '''microgametocyte''', divide into a large number of small cells with flagella. The motile microgametocytes are released from the parasitised cell as it ruptures. A single microgametocyte will penetrate a macrogametocyte and the nuclei of both cells will fuse. A wall then develops around the new '''oocyst''' which then remains in this stage of development until released from the body in the hosts faeces. Sporogony will then begin as described above.
 
  
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{{Learning
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*The schizont contains numerous elongated '''merozoites'''
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|literature search  = [http://www.cabdirect.org/search.html?rowId=1&options1=AND&q1=Coccidia+&occuring1=title&rowId=2&options2=AND&q2=%22Life+Cycle%22&occuring2=title&rowId=3&options3=AND&q3=&occuring3=freetext&x=55&y=18&publishedstart=yyyy&publishedend=yyyy&calendarInput=yyyy-mm-dd&la=any&it=any&show=all Coccidial Life Cycle publications]
 
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*The formation of merozoites is the first asexual reproductive stage called '''schizogony'''
  
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{{review}}
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*The schizont ruptures releasing the merozoites which also invade the epithelial cells
  
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==Webinars==
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*Another generation of schizonts form which is the beginning of the sexual phase of reproduction called '''gametogony'''
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<rss max="10" highlight="none">https://www.thewebinarvet.com/parasitology/webinars/feed</rss>
 
  
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[[Category:Coccidia|A]]
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*The merozoites form male '''microgamonts''' or female '''macrogamonts'''
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**Collectively known as gamonts or gametocytes
  
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[[Category:Expert_Review]]
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*The microgamonts released from the microgametocyte penetrate and fertilise the macrogamont (which is contained within the macrogametocyte)
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*Gametogony forms the '''zygote'''
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**Surrounded by a cyst wall
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**Forms the '''oocyst'''
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*The oocyst is passed in the faeces and is unsporulated
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*The oocyst becomes sporulated in the second asexual reproductive phase called '''sporogony'''
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*Once the oocyst is sporulated it is infective
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[[Category:Coccidia]]
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[[Category:Parasites]]
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[[Category:To_Do_-_Parasites]]
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[[Category:To_Do_-_NickJ]]
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[[Category:1990_Graduate_-_Australia_-_University_of_Sydney_Faculty_of_Veterinary_Science]]

Revision as of 18:01, 17 July 2010


 This article is still under construction.


Coccidia - Joel Mills

Coccidia have three major stages to their life cycle: Sporogony, Schizogony, Gametogony. The first two stages are asexual, with sexual reproduction occurring in the third stage.

Sporogony

This is the fist stage of the coccidia life cycle and occurs exogenously in the environment. Sporozoites develop within the oocyst before it becomes infective. Once the sporozoites have been formed the oocyst is infective and on ingestion by the host will release sporozoites to invade intestinal epithelium.

Schizogony

Sporozoites grow within intestinal epithelial cells

    • Sporozoites feed and grow
  • As the sporozoite grows the nucleus divides forming a schizont
  • The schizont contains numerous elongated merozoites
  • The formation of merozoites is the first asexual reproductive stage called schizogony
  • The schizont ruptures releasing the merozoites which also invade the epithelial cells
  • Another generation of schizonts form which is the beginning of the sexual phase of reproduction called gametogony
  • The merozoites form male microgamonts or female macrogamonts
    • Collectively known as gamonts or gametocytes
  • The microgamonts released from the microgametocyte penetrate and fertilise the macrogamont (which is contained within the macrogametocyte)
  • Gametogony forms the zygote
    • Surrounded by a cyst wall
    • Forms the oocyst
  • The oocyst is passed in the faeces and is unsporulated
  • The oocyst becomes sporulated in the second asexual reproductive phase called sporogony
  • Once the oocyst is sporulated it is infective
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