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2014-11-13 05:49:30
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  1. General morphological features of Cestodes
    • No digestive system
    • skeletal, circulatory, and respiratory systems absent
    • acoelomate (parenchyma fills body cavity)
  2. Major differences between cestodes and trematodes
    • shape: Cestodes are ribbon-like (not leaf-like)
    • proglottids: Cestodes are made up of hermaphroditic pseudosegments
    • feeding: Cestodes lack mouth and digestive tract
    • Cestodes are exclusively endoparasitic in gut
    • Cestode larvae infects vertebrates and invertebrates
  3. What is the proposed evolutionary history of cestodes?
    • Free living
    • Developed suckers, became ectoparasites
    • Migrated internally, adapted to physiological conditions (evolved tegument, lost gut, amplification of repro system)
  4. define polyzoic, monozoic, apolysis, strobilization, anapolysis
    • polyzoic: many proglottids (normal)
    • monozoic: one proglottid (rare)
    • apolysis: release of gravid proglottids from host
    • strobilization: forming proglottids (AKA forming strobila)
    • anapolysis: proglottids disintegrate en route, releasing eggs
  5. Describe the general anatomic features of Cestodes ("head area")
    • Scolex: "head area"
    • armed with suckers, spines, hooks, etc
    • 2 types of scolex...
    • Rostellum: small rounded projection bearing hooks on apex of some tapeworms
    • 1) Acetabulate: cup shaped, circular, and has 4 suction cups w/ equal spage
    • can be "armed" or unarmed
    • 2) Bothraite: presence of 2-6 bothria (longitudinally arranged shallow grooves w/ weak suction)
  6. Describe the general anatomic features of Cestodes ("non-head area")
    • Neck: (AKA zone of proliferation) contains stem cells
    • unsegmented
    • site of proglottid formation
    • Strobila: chain of proglottids
    • sexual maturity is reached in posterior proglottids (3 regions)
    • immature proglottids: reproductive organs visible, nonfunctional
    • mature proglottids: reproductive organs fully functional (self-fertilization)
    • Gravid proglottids: filled with eggs or shelled embryos
  7. Describe the differences in tegument of cestodes
    • microtriches: tiny projections from tegument
    • provide resistance to peristalsis
    • increase accessability to nutrients (agitate host)
    • Glycocalyx: covers entire surface
    • protects worm from digestive enzymes
    • enhances nutrient absorption
    • tegument musculature: layers of muscles between the two cytoplasmic regions
  8. Describe the general reproductive system of cestodes (differs from trematodes? Sperm pathway, ova pathway)
    • Monoecious
    • Unlike trematodes...
    • 1) Uterus meats with dead-end
    • 2) Separate vaginal canal is present
    • 3) self fertilization within a proglottid may occur
    • sperm pathway: testis -> vas efferens -> vas deferens -> cirrus
    • ova pathway: ovary -> oviduct -> ootype -> uterus -> uterine pore
    • ootype is joined by duct of seminal recepticle, surrounded by Mehlis gland, and joins with vitelline duct
  9. Describe the general female reproductive system in cestodes
    • vitelline glands -> 1* vitelline ducts -> common vitelline duct
    • vitellaria: collective name for vielline glands
    • help in yolk and shell formation
    • vagina: carries sperm to oviduct where fertilization occurs
    • seminal receptical: stores sperm
    • eggs are constantly produced and expelled through uterine pore
    • uterus becomes swollen with eggs, and gravid proglottid detaches from host
  10. Describe general reproduction in Cestodes
    • Cirrus of one proglottid is inserted into vagina of another proglottid (same or diff worm)
    • Sperm is stored in seminal receptacle
    • Hypodermic impregnation: cirrus forced through body wall
    • cross fertilization preferred
  11. Describe the egg morphologies found in Cestodes
    • Oncosphere: analogous to mericidium
    • embryophore: surrounds oncosphere
    • Pseudophyllidean eggs: morphologically and developmentally similar to trematode eggs
    • thick brown/yellow shell
    • operculum
    • ciliated embryophore
    • many vitelline cells
    • Dipylidium eggs: thin shell
    • nonciliated embryophore
    • thick outer envelope
    • few vitteline cells
    • Taeniidae eggs: no shell or outer envelope
    • thick, nonciliated embryophore is outermost covering
    • very few vitelline cells
  12. Describe general lifecycle pattern of Cestodes
    • 2 fundamental patterns
    • 1) Pseudophillidean
    • Eggs: exit host in feces and reach water
    • Coracidia: escapes from shell through operculum and swims using ciliated embryophore
    • Penetrates aquatic arthropod (not snail)
    • procercoid: after loss of cilia
    • oncosphere hooks are retained in cercomer (tail-like structure)
    • second intermediate host (fish) ingests arthropod
    • procercoid migrates to various parts of the body and transforms into...
    • plerocercoid: found in second intermediate host
    • shows initial formation of scolex and strobila
    • infective stage
    • strobilization occurs in small intestine after ingestion
    • 2) Cyclophyllidean
    • Egg: inactive until eaten by intermediate host (vert/invert)
    • No operculum
    • eggs hatch in the gut
    • Oncosphere: unciliated
    • uses its 6 hooks to enter hemocoel of intermediate host
    • Cysticercoid: immature adult with fully developed scolex
    • surrounded by several cystic layers
    • cystic layers dissolve in gut and strobilization occurs
    • Oncosphere: enters intestinal lining, then venule
    • carried to varying areas, develops into...
    • cysticercus: Taenia spp
    • AKA bladderworm
    • coenurus cysts: 
    • hydatid cyst: