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Taenia proglottid comparison chart from Brown and Belding(3)
Both species of Taenia have a typical life cycle, but T. solium has the ability to autoinfect. In the typical life cycle, the worms present in the intestine of man expel their eggs in the gravid proglottids that separate from the main body of the worm and are passed in feces. New proglottids are formed from the scolex. The eggs are then ingested by cattle or pigs along with their feed. In both species the embryo hatch from the egg and penetrate the mucosa gaining access to the blood they travel to various tissues in the animals body to form cysticerci.
Ingestion of undercooked pork or beef containing cysticerci allow the adult worm to mature in humans. Autoinfection occurs when man is infected with Taenia solium. The embryo hatch from the egg in the intestine and penetrate the intestinal wall where they gain access to the blood stream and travel to various tissues in our body to form cysticerci. This condition is called cysticercosis.
Because T. saginata cannot be differentiated from T. solium by the morphology of their ova alone, it is necessary to obtain a gravid proglottid in saline for india ink injection or a proglottid in formalin for section and staining with H&E. If however a scolex is recovered and it does not have hooklets visible it is that of Taenia saginata.
In both cases it is necessary to count the number of lateral uterine branches on one side of the main branch of the uterus. Ink injection method is as follows.
A note on section and staining. If the proglottid is received in formalin or SAF it may be sectioned and stained in Haematoxylin and Eosin.
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