Taenia saginata
is a multicellular parasite that is commonly called the "beef tapeworm". It is a flatworm (phylum Plathelminthes ) and a tapeworm (class Cestoda ). Lacking their own digestive system, adults live in the intestinal tract of infected humans, where they may reach a length of 25 meters. Ova, produced in the body segments (proglottids ) are shed in the feces. These ova may contaminate vegetative matter, soil or fresh water, where they can be ingested by cows. The ova hatch in the cow's intestine, liberating larvae that find their way into the cow's muscle. Humans become infected when they ingest improperly cooked beef. The scolex (head) of the adult attaches to the intestinal mucosa. The worm begins to grow, elongating as proglottid segments are added. Ova are produced in the proglottids and shed in the feces. Diagnosis depends on finding ova or proglottids in the feces.
Image 1 is the scolex, which possesses four suckers. A plastic model of the scolex is shown in slide 2. Slide 3 shows a proglottid in which the uterine branches have been injected with dye. Taenia saginata has more than 15 lateral branches on each side of the uterus. Slides 4 through 10 show Taenia saginata ova, which are indistinguishable from that of Taenia solium or Echinococcus granulosus.
Click on each image to see the enlarged version.
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| 1.scolex 43 X | 2. model of scolex | 3. proglottid 70 X | 4. ova 400 X | 5. ova 400 X |
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| 6. ova 400 X | 7. ova 1000 X | 8. ova 1000 X | 9. ova 1000 X | 10. ova 1000 X |
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