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Laboratory 7
TREMATODES AND ACANTHOCEPHALANS
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| Gyrodactylus sp. This monogenean trematode is an ectoparasite of fish. Note the haptor ("holdfast organ") at the posterior of the worm. |
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| Fasciola hepatica - Eggs Note the size, shape, color, and the operculum. |
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| Fasciola - miracidium Note the cilia, eye-spots and the germ cells. |
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| Limnea spp. One of the many snail intermediates hosts suitable for the development of Fasciola stages. |
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| Fasciola - Redia Characterized by a primitive digestive tract made up of a pharynx and intestine. Note the developing cercariae within the redia. |
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| Fasciola - cercaria Note the oral and ventral suckers. Also note the tail for swimming. |
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| Fasciola hepatica - metacercaria
The encysted metacercaria would normally be found on vegetation. |
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| Fasciola hepatica Adult specimen taken from the bile duct of an infected animal. Note the size, distinct cone at the anterior end, " shoulders" and broad outline. |
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| Model of a Sheep Liver infected with Fasciola hepatica Note the thickened, calcified bile ducts and the adult worms in the bile ducts (difficult to see in this photo). |
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| Fascioloides magna Very large liver fluke. Indigenous to North Americana. Normal Host
Abnormal Host |
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| Dicrocoelium dendriticum - Eggs These eggs are small, dark brown and asymmetrical, they are thick walled with an indistinct operculum. |
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| Dicrocoelium dendriticum Adult specimen taken from the bile duct of an infected animal. Note the small size, lancet shape, absence of distinct cone at the anterior end, no "shoulders", narrow outline. Compare with Fasciola hepatica |
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| Paramphistomum cervi The rumen fluke of sheep and cattle. Note the thick, circular fleshy character of the specimens in the bottom of the jar. Also the flukes buried in the rumen papillae. |
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| Paragonimus kellicotti This trematode occurs in the lungs of dogs, cats, and wild carnivores and is found in fibrotic lung cysts. The second intermediate host is a crayfish. (What is the first intermediate host?) |
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| Paragonimus kellicotti - Eggs These are large yellowish-brown operculated eggs that are found in the feces (or demonstrated in the sputum). They measure 75-118 u X 42-67 u and have a marked "shoulder" or "ridge" surrounding the operculum. |
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| Heterobilharzia americana Adult worms from the mesenteric veins of a dog. The male is the larger of the two, and has the gynaecophoral groove where the female resides following mating. Separate sexes are the distinguishing feature of the schistosomes. |
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| Review Question:
The worms at the left were recovered from the bile duct of a deer in upper New York state. A. Identify the worms (Genus and species) B. How did the deer acquire the infection? |
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