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Platyhelminthes pt 2

Platyhelminthes pt 2. Digene trematodes and tapeworms. Opisthaptor Ectoparasite One host. Trematoda. Acetabulum endoparasite Mollusc/vertebrate life cycle. Cestoda. Monogenea. Turbellaria. Free living. Microtriches Scolex Proglottids. Cilia lost from ectoderm

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Platyhelminthes pt 2

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  1. Platyhelminthes pt 2 Digene trematodes and tapeworms

  2. Opisthaptor Ectoparasite One host Trematoda Acetabulum endoparasite Mollusc/vertebrate life cycle Cestoda Monogenea Turbellaria Free living Microtriches Scolex Proglottids Cilia lost from ectoderm (parasitic lifestyle) Phylum Platyhelminthes

  3. 2 or more hosts Endoparasitic No cilia on skin, skin is syncytial Life cycle: Adults in definitive host (a vertebrate) reproduce sexually → eggs in host’s feces released into water → hatch into ciliated larva (=miricidium) → snail (intermediate host) → asexual reproduction → sporocyte → redia → cercaria released from snail → metacercaria encysts in 2nd intermediate host (or forage in some cases) → ingested by definitive host Di(2)-Gene(birth)

  4. Schistosoma mansoni

  5. 200 million infected worldwide Leading cause of death of Egyptian men 20-44 years old Adults live in mesenteric veins, veins associated with bladder Damage caused by unegested eggs (50% never released) Control: clean water, sewage control, snail reduction Exacerbating factors: poverty & ignorance, dams

  6. Swimmer’s itch • Schistosoma sp. that infect ducks, muskrat

  7. Blackspot disease: Uvulifer sp.

  8. Fasciola hepatica (sheep liver fluke)F. gigantica (human liver fluke)

  9. Dicrocoelium dendriticum = a bile duct fluke of ruminants such as sheep, goats, deer, pigs.

  10. 3rd Annual Tri-Sci Athlon Tuesday November 13th CMU Ballroom Make a team of 3 – 4 students & sign up on the poster outside SL 118 by October 16th!! For more information: Tri-Beta Meeting October 2nd 6:00 SL118 Chem Club Meeting October 3rd 7:00 HA 405 Or contact Marissa Schafer at marissaschafer@hotmail.com

  11. Opisthaptor Ectoparasite One host Trematoda Acetabulum endoparasite Mollusc/vertebrate life cycle Cestoda Monogenea Turbellaria Free living Microtriches Scolex Proglottids Cilia lost from ectoderm (parasitic lifestyle) Phylum Platyhelminthes

  12. Class Cestoda - Tapeworms • Obligate endoparasites of vertebrates • Lack digestive tract • Have scolex for attachment to host • Body divided into proglottids • Each proglottid = egg factory with its own ovary and testis (make up to 50,000 eggs per proglottid) • Worm = hundreds to thousands of proglottids

  13. General life cycle of tapeworms • Adult in intestine of definitive host → proglottids break off and pass with feces → eggs released from proglottid → eaten by intermediate host → oncosphere larva → intermed host ingested by definitive host → adult develops in intestine

  14. Tapeworms Scolex

  15. Echinococcus granulosis – a tapeworm of dogs & dingoes

  16. Dipylidium caninum

  17. Beef tapeworm: Taenia saginata Attains a length of 10m

  18. Ligula intestinalis • Egg → copepod (encycts as a procercoid) → fish (encysts as a plerocercoid larva) → ingested by final host → adult tapeworm in gut of bird

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