10. Life cycle and description of larval stages of cyclophyllida Flashcards
(13 cards)
What type of life cycle do cyclophyllida have?
Indirect
Require only 1 intermediate host (IH) except for Mesocestoides
What are the characteristics of cyclophyllida eggs?
Embryonated, non-operculate, non-ciliated (oncosphere), varying shape, size and colour, hexacanth larvae (six hooklets), three thick shells
How are embryonated eggs or proglottids of cyclophyllida transmitted?
Passed in faeces, then eaten by intermediate host (IH)
What happens after the definitive host (FH) ingests the intermediate host (IH)?
Larvae develops to adult tapeworm in the intestine of FH
What do adult tapeworms release into the environment?
Embryonated eggs or gravid proglottids
Define cysticercoid.
A metacestode with a single non-invaginated scolex drawn into a small vesicle, practically no cavity
What is a cysticercus?
A single invaginated scolex with a fluid filled cavity
Examples include cysticercus cellulosae (larval stage of Taenia solium), cysticercus pisiformis (T. pisiformis), cysticercus bovis (T. saginata)
What is coenurus?
A large fluid containing bladder with multiple invaginated scolexes attached to the wall
for meg: a large fluid filled bladder with multiple invaginated scolices attached to the inner cyst wall (aka germinal layer). Bladder - a large, thin walled structure
Example: T. multiceps containing about 300 metacestodes
Describe tetrathyridium.
An elongated, solid-bodied metacestode with deeply invaginated acetabular scolex, usually one metacestode but can divide into two. Usually 1 metacestode, but can divide into 2.
Mesocestoides.
What is a strobilocercus?
A single scolex not invaginated when fully developed, attached to the bladder by a long, segmented strobila
Example: Taenia taeniaeformis
What does a hydatid/echinococcus produce?
Multiple infective stages (protoscolices) from the germinal layer of the cyst or by forming brood sacs (hydatid sand)
Examples: E. granulosus (endogenous budding), E. multilocularis (exogenous budding)
Fill in the blank: A cysticercus is a single _______ with a fluid filled cavity.
invaginated scolex
True or False: Cysticercoids have a cavity.
False
