Lab 8 Flashcards
Cestodes
-the “head” region of the tapeworm
SCOLEX
scolex is equipped with some sort of holdfast organ – some variations include:
1) suckers 2) hooks 3) grooves
-the types of sucker-like organs on scolices of cestodes that infect man:
1) Acetabula (sing. acetabulum)
2) Bothria
Acetabula (sing. acetabulum)
- _____ or ______shaped with muscular wall
- usual pattern:
- circular or oval cup
- 4 equally spaced around scolex
Bothria
Shape:
Usually __ in number
-________ location on scolex
- “Slit-like” shallow pits or long grooves
- 2
- Lateral or dorsoventral
protruding dome-shaped area on anterior end of scolex
Rostellum
- “armed” -
- “unarmed” -
- hooks are arranged on it This is the rule.
- no hooks
(presence and absence of ______ and shape and arrangement of _____
are identification keys in cestodes)
- rostellum
- hooks
region between scolex and strobila segments
neck
contains stem cells that give rise to new proglottids
neck
long chain of proglottids (segments)
depending upon species, from a few to thousands of proglottids
strobila
Strobila
-each has sets of reproductive organs of ____ -“_____” in each set
- both sexes
- genitalium
growth of strobila is called:
strobilization
strobilization occurs from _____ end as new proglottids are added
anterior
proglottids closest to scolex –
most immature
“gravid” =
filled with eggs
proglottids in strobila “_____fertilize” (rarely self-copulate within same proglottid)
-cross
How proglottids are shed: depends upon:
species of cestode
3 ways proglottids are shed:
- intact gravid
- proglottid disentigrates as shed and eggs go out with feces
- eggs shed from attached proglottid through uterine pore
-means an empty, formerly gravid proglottid
“Senile”
Tegument is important in: (3)
- absorption (cestodes dont have GI tract)
- excretion of wastes
- osmoregulation
how does tegument effectively absorb nutrients?
-covered in microvilli called “microtriches” even on the suckers – increases
the absorptive area of tegument
MUSCULAR SYSTEM:
- each proglottid has two layers of muscle:
- enables each segment to:
- longitudinal, transverse
- move independently
NERVOUS SYSTEM:
- well developed in cestodes
- sensory: ____receptive, _____receptive
-tacto, chemo
Which is rare in cestodes? monecious or dioecious?
dioecious
dioecious cestodes do not infect:
man or his domestic animals
______ reproduction is the Rule in cestodes
MONECIOUS
-cestode fertilization occurs when repro systems ______
mature (as proglottids proceed toward posterior part of strobila)
-self-mating within the same proglottid is the _____, not the ____.
-exception, rule
sperm are transferred between:
mature proglottids that lie next to each other in intestine of definitive host
-gravid proglottids – contain _____# of eggs
100’s to 1000’s
2 different types of cestode egg shells?
Dipylidium type, taenia type
Which type of egg shell is thin?
Dipylidium
Which type of egg shell is thick?
Taenia
Taenia type egg shell contain a _______ embryo within
hexacanth
which species have a dipylidium type shell?
Diphyllobothrium latum
Dipylidium caninum
Hymenolepsis nana and H. diminuta
which species have a taenia type shell?
Taenia sp., Echinococcus sp.
-Most cestodes require minimum of two hosts for completion of cycle. There is always an exception:
________ can complete life cycle in same host.
– ________ host is optional for H. nana
- Hymenolepsis nana
- Invertebrate intermediate
Cestode life span depends on species, but can last from _____ to _____
days, years
_______ -the hexacanth larva in the egg
ONCOSPHERE
________- juvenile (larval) form of tapeworm found in intermediate hosts
METACESTODE:
general life cycle of cestodes
egg –�oncosphere (in egg) �– metacestode (in intermediate host)� –adult worm (in definitive host)
