2011Cestodes - 10/16/2011 Protozoa: Single Celled Organisms...

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10/16/2011 1 Protozoa : » Single Celled Organisms » Eukaryotic Platyhelminthes - Flatworms Trematodes, Cestodes - Nematodes – Roundworms Arthropods Cestodes • Phylum Platyhelminthes (flatworms) – Class Trematoda (flukes) Class Cestoidea (tapeworms) Lack a mouth and digestive tract. – Subclass Eucestoda (true tapeworms) – Order Pseudophyllidea » Genus Diphyllobothrium, – Order Cyclophyllidea » Genera: Taenia, Hymenolepis, Dipylidium
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10/16/2011 2 General Characteristics Morphology • Multi-segmented and up to 25m long. Scolex - at anterior end functions in attachment Neck - narrowest part of the worm Strobila -made up of segments of the worm called proglottids .
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10/16/2011 3 Scolex Acetabulate - has four suckers or muscular cups. May have an armed rostellum. Bothriate - two, four or six longitudinally arranged shallow depressions
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10/16/2011 4
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10/16/2011 5 Tegument • Lined with microvilli – Glycocalyx – Microthrices (microthrix) • Nutrient absorption • Tegumental and parenchymal musculature – circular and longitudinal muscles Parenchyma- space enclosed by tegument • Cestodes have a well developed nervous system . A ‘brain’ in scolex is connected via nerves to the strobila. Reproductive organs and musculature in proglottids are extensively innervated. • Osmoregulatory and excretory system- collecting canals (ventral from scolex; dorsal to scolex)
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10/16/2011 6 Reproductive System • Proglottid has male and female organs • Proglottids on the same worm or another worm can engage in mating. Anapolytic worms ( Diphyllibothrium ) tanned eggs exit through uterine pore. Apolytic worms – entire gravid proglottid is released – no uterine pore ( Dipylidium) Egg • Egg is encased in a shell • Layered – outer envelope – embryophore – inner envelope – oncosphere - embryo is equipped with hooks and will give rise to larval form. Contain vitteline cells as food source
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10/16/2011 7 Pseudophyllidean eggs are tanned, have a ciliated embryophore and have an operculum at one end. From within the oncosphere a coracidium emerges (seen in Diphyllobothrium latum ). Dipylidean eggs are thin shelled, have a relatively thick outer envelope and a non-ciliated embryophore ( Dipylidium and Hymenolepis ). Taenoid eggs lack shell and outer envelope. Embryophore is outermost covering ( Taenia and Echinococcus ). Life Cycle Patterns Pseudophyllidean pattern Eggs released through uterine pore are expelled in feces. Coracidia emerge and swim around
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This note was uploaded on 11/21/2011 for the course ZOO 4232 taught by Professor Kima during the Fall '10 term at University of Florida.

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2011Cestodes - 10/16/2011 Protozoa: Single Celled Organisms...

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