Cestoidea: Form and Function Flashcards
What is a scolex?
The ‘head’ or holdfast organ of a tapeworm, which may have suckers, grooves, hooks, spines, glands, or tentacles.
It contains the neural ganglia of the worm.
What is the neck of a tapeworm?
An undifferentiated zone located between the scolex and the strobila, containing stem cells responsible for giving rise to new proglottids.
What is a strobila?
The region of a tapeworm behind the scolex and neck; it is a chain of proglottids.
What is a proglottid?
A segment in a strobila that includes male and female reproductive organs.
A proglottid can copulate with itself, with others in its strobila, or with those in other worms, depending on the species.
What does polyzoic mean?
A strobila consisting of more than one proglottid.
What does monozoic mean?
A tapeworm whose strobila consists of a single proglottid.
What is strobilation?
The formation of a chain of proglottids by budding.
What is a gravid proglottid?
A proglottid containing fully developed eggs or shelled embryos.
What is apolysis?
The disintegration or detachment of a gravid tapeworm segment.
What is anapolysis (pseudoapolysis)?
The detachment of a senile proglottid after it has shed its eggs.
What is hyperapolysis?
The detachment of a proglottid while still immature, before eggs are formed.
May lead to an independent existence in the gut while maturing.
What is craspedote?
The posterior edge of each segment overlaps the anterior edge of the next segment.
What is acraspedote?
The posterior edge of a proglottid does not overlap the anterior edge of the next.
What are acetabula?
Suckers on the scolex of a tapeworm; normally 4 acetabula on a scolex.
What are bothridia?
Usually in groups of 4; can have highly mobile, leaflike margins with adaptations for adhesion.
What is a rostellum?
A dome-shaped area on the apex of the scolex, often with hooks.
What are bothria?
Usually 2 in number (dorsal and ventral), and take the form of shallow pits.
What is the tegument?
The outer layer of cestodes, which is a syncytium and lacks a digestive tract.
All required substances are absorbed through their tegument.
What are microtriches?
Numerous minute finger-shaped tubes that extend out of the tegument, increasing the absorptive area.
They completely cover the worm’s surface.
What is the muscular system of cestodes?
Muscle cells consist of contractile myofibrils and non-contractile myocytons, with bundles of longitudinal and circular muscle fibers lying below the distal cytoplasm.
What is the nervous system of cestodes?
Displays the organ system typical of platyhelminthes, with the main nerve center located in the scolex.
What is the excretion and osmoregulation system in cestodes?
Main excretory canals run from the scolex to the posterior end of the strobila, emptying when terminal proglottids detach.
What is the reproductive system of cestodes?
Typically monoecious, with few exceptions, where sperm is transferred and oocytes are fertilized in immature proglottids.
What is protandry in cestodes?
The maturation of male gonads first, followed by female gonads, which may prevent self-fertilization of the same proglottid.
