Cestodes Flashcards
cestodes: general characteristics
- all are parasitic: adults in sm. intestine of vertebrates, larvae in invertebrates or vertebrates
- no digestive, circulatory, respiratory or skeletal systems
- muscular system & nervous system
- body of scolex (mouth) & proglottids (body segment)
- hermaphroditic
cestodes - taxonomy
cestodes aka tapeworms are a class of platyhelminthes aka flatworms
proglottid types
immature proglottids - anterior end
mature proglottid - middle of body
gravid proglottid - toward posterior, full of eggs,
species specific in both IH and DH
two orders within cestodes
- cyclophyllideans = true tapeworms
2. pseudophyllidea = pseudotapeworms
general characterisitcs of cyclophyllideans (true tapeworms)
- has a scolex of 4 different suckers (can be armed or unarmed)
- proglottids (NO uterine pore)
- each egg can form one tapeworm
- IH must ingest eggs
- metacestode - larvae DH must ingest
cysticercoid
- single scolex NOT invaginated
- usually seen in invertebrate IH like fleas or mites
- this is a TYPE of metacestode
cysticercus
single invaginated scolex usually vertebrate IH
- inside out, small fluid-filled bladder
- a TYPE of metacestode
coenurus
a large fluid-filled bladder containing multipe invaginated soclices in vertebrate IH
goal of the cyclophillidean
KILL the IH because it cannot complete its life cycle until its eaten by the DH
unilocular hydatid cyst
broad capsules with 100s - 1000s of protoscolices, very large, thick-walled filled with fluid
multilocular hydatid cyst
not contained by the thick-walled compartment
characteristics of Pseudophyllideans
scolex: bothria = 2 slit-like structures (no hooks or suckers)
proglottids - 1 set of repro organs, central genital pore
- uterine pore in center
- eggs are operculated and WILL float in fecals!
- larvae have a metacestode in IH
diagnosis of cestodes (tapeworms)
fecal floatation
simple vs. centrifugal fecal flotation
flotation is how you find most nematod eggs, larva and tapeworm eggs.
- need at least 1 gm
- use correct soln
- for simple, it must SIT for 15-20min
Dipylidium caninum : taxonomy
part of order cyclophyllidean class cestodes phylum platyhelminthes