Lab Exercises
Phylum PLATYHELMINTHES
Class Cestoda
Tapeworms of small animals
Diphyllobothrium latum: dog, cat, mink, seal, human - Freshwater fish life cycle
Spirometra mansonoides: cats - Frog or Watersnake life cycle
Mesocestoides: dog, cat - Arthropod/Vertebrate life cycle
|
|
Mature Mesocestoides corti proglottid.
Note the paruterine organ (to the left in the photo). Gravid, "club-shaped" proglottids pass in the feces |
Mesocestoides corti eggs
These eggs were expressed from a gravid proglottid. They measure 40 to 60 µm in diameter. |
Dipylidium caninum: dog, cat - Flea life cycle
|
|
Dipylidium caninum
Adult worms may reach up to 50 cm in length. |
Dipylidium caninum egg packets
Each egg packet contains up to 20 eggs and within each is an onchosphere bearing 3 pairs of hooks. The egg packets pass from the dog within the gravid proglottid, from which they must be expressed for identification. |
 |
Dipylidium caninum proglottids on feline feces
At least 7 proglottids can be seen on this fecal specimen:
Four are near the kitty-litter and 3 others are to the right of the
kitty-litter.
These proglottids are usually noticed by the owner who will tell you they saw "rice grains" or tapeworms in the cat's stool. The segments may or may not be in the sample that is brought to you as the proglottids are motile. |
Top of Page
Taenia sp.: dog, cat - Small Mammal or Human/Livestock life cycle
|
|
|
Taenia saginata
Cysticerci in the heart of a cow. |
Taenia saginata Cysticerci
Note that many of the protoscoleces have everted. |
Taenia taeniaformis
Adult worms |
Click here to link to a video of a live Taenia taeniaformis proglottid
Echinococcus granulosus: dog - Sheep life cycle
|
|
|
Adult
Echinococcus granulosus |
Stained adult
Echinococcus granulosus |
Adult Echinococcus granulosus
in
situ (dog small intestine)
|
|
|
Echinococcus granulosus
Hydatid cysts in the liver of a sheep. |
Echinococcus granulosus
Hydatid cysts being removed from the liver of a human. |
| |
|
|
Diagram of a hydatid cyst. |
|
Cross section of a hydatid cyst. Host tissue can be seen in the upper left corner, then the wall of the cyst, the germinal layer and finally a daughter cyst, containing protoscoleces, floating free in the fluid-filled interior. |
Click here to link to the Echinococcus granulosus life cycle.
Tapeworms of large animals
Moniezia expansa: sheep - Mite life cycle
 |
Moniezia expansa adult
The adult of this large tapeworm (up to 6 m) is found in the small intestine of sheep (esp. lambs).
The intermediate host is a free-living mite. |
 |
Moniezia expansa eggs
Triangular in shape, contain a "pyriform apparatus," and
measure approximately 56 to 67 µm. |
Anoplocephala sp.: horse- Mite life cycle
 |
|
 |
Anoplocephala magna (top) and A. perfoliata (bottom) adults |
Anoplocephala perfoliata adult tapeworms are found around the
ileo-cecal junction of horses.
There are "lappets" just below each sucker (best seen on the top middle worm in the photo). |
Anoplocephala perfoliata egg -
measures about 65 to 85 µm.
Note the "pyriform apparatus" around the oncosphere in the center of the egg. |
Top of Page
Phylum ACANTHOCEPHALA
Macracanthorhynchus hirudinaceus: swine - Junebug Grub life cycle
|
|
Macracanthorhynchus hirudinaceus
spiny proboscis ("thorny-head")
|
Macracanthorhynchus hirudinaceus
Enlargement of the hooks on the proboscis, used to anchor the worm to the gut wall.
|
 |
Macracanthorhynchus hirudinaceus adults attached to the wall of a pig's small intestine. While similar in size to Ascaris suum, these worms, in life, are flattened and have pseudosegmentation. |
 |
Macracanthorhynchus hirudinaceus egg
Note the multiple layers of shell and the larva (acanthor) inside.
These eggs measure 80 X 62 µm. |
Top of Page
|
