Toxoplasma gondii

Toxoplasma gondii can infect the intestinal epithelium of cats and undergo a life cycle fairly similar to Eimeria stiedae. Infection is by ingestion of a sporulated oocyst. However, when a cat, or other mammal, ingests a sporulated oocyst, an extra-intestinal sequence of development can occur. When ingested the oocyst releases the sporozoites which then penetrate an intestinal epithelial cell or may enter the circulatory system and be carried to various tissues throughout the body, and penetrate cells and begin to divide rapidly, producing tachyzoites. After 8-16 tachyzoites are produced the host cell ruptures and the tachyzoites penetrate new host cells, repeating the rapid division. As the infection becomes chronic the rate of division declines, but many more zoites (now termed bradyzoites) accumulate in each cell. A wall forms around them and they are called a zoitocyst. The epidemiology of toxoplasmosis is complex. Infection can result from ingestion of the oocysts, meat containing zoitocysts or free bradyzoites, and also infection of the foetus by an infected mother. Toxoplasmosis may not produce gross pathology, but can cause extensive tissue destruction in muscle, nerve, and epithelial tissues. Infection of the foetus may result in abortion or deformity of the offspring. The stage of Toxoplasma gondii on your slide is one of the zoites (either tachyzoite or bradyzoite). Don't waste too much time trying to study the anatomy. It is extremely minute and is hard to see even using oil immersion.

Toxoplasma gondii zoite