Laboratory 6
PLATYHELMINTHS AND ACANTHOCEPHALANS
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Card 7:3
| 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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Card 7:17
| 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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Card 7:18
| 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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| Diphyllobothrium latum (Cestoda: Pseudophyllidea) Segments of the broad fish tapeworm of man and dogs. |
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| Diphyllobothrium latum - eggs Note the light brown color, shape, size (approximately 60 X 45 microns), and they are operculated (the operculum is indistinct in a fresh preparation). The eggs are not embryonated when passed in the feces. |
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| Spirometra mansonoides
(Cestoda: Pseudophyllidea) Portions of an adult worm. Note the line of brown spots going up the center of the worm. These are the uteri of the proglottids filled with brown eggs. Eggs (not segments) are found in the feces. From the small intestine of a cat. |
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| Mesocestoides - gravid proglottid
(Cestoda: Cyclophyllidea) Uterus lies in the mid-line of the proglottid. The eggs pass from this to be stored in the parauterine organ which can be seen as a thick-walled structure at one end of the proglottid. |
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| Mesocestoides sp. Tetrathyridia removed from the peritoneal cavity of a dog. Note the size, and gross appearance (resemble "cream of wheat" particles). |
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| Dipylidium caninum proglottid
(Cestoda: Cyclophyllidea) Found in the small intestine of the dog, cat, and occasionally man. Note the two sets of reproductive organs in each segment. The gravid segments contain numerous "egg packets", the other reproductive organs having degenerated. |
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| Dipylidium caninum - egg packets
The egg packets contain 15-20 eggs in each and are seldom seen free in the feces. They may, however, be readily expressed from the gravid proglottids. |
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| Cysticercoid This tapeworm larval stage is found in arthropods. It is the metacestode stage of Dipylidium caninum, Anoplocephala spp., and Moniezia spp. |
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| Taenia taeniaeformis - adults
(Cestoda: Cyclophyllidea) This is known as the "broad necked' tapeworm of cats. The neck is almost as broad as the scolex and segmentation begins immediately behind the scolex. |
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| Strobilocercus This is the larval stage of Taenia taeniaformis which has been removed from the intermediate host (a mouse). |
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| Taenia taeniaeformis - Strobilocercus
Note the pea-sized nodules containing the larval worms embedded in the liver. These are young larvae and the protoscoleces are still invaginated. |
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| Taenia pisiformis - Adult
(Cestoda: Cyclophyllidea) Adult from the small intestine of a dog. Note the lateral genital pore on the gravid proglottids and how it alternates sides irregularly. |
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| Cysticercus This is the larval stage of members of the genus Taenia. Note in this specimen the protoscolex is everted. Normally it would be found inside of the "bladder". |
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| Taenia crassiceps
(Cestoda: Cyclophyllidea) Cysticercus of T. crassiceps (left) from the peritoneal cavity of a groundhog. (Note the fluid filled bladder with protoscolex at one end). Cysticercus of T. pisiformis from a rabbit peritoneal cavity is similar to T. crassiceps, but larger (not shown). Image on right is a bottle filled with Taenia cysticerci from the peritoneal cavity of a groundhog. |
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| Taenia saginata- cysticercus
(Cestoda: Cyclophyllidea) Cysticercus of Taenia saginata in the skeletal muscle of a cow. Note the pea-sized cysts. |
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| Taenia multiceps - coenurus
(Cestoda: Cyclophyllidea) This slide shows a cross section through the larva (coenurus). Note the many protoscolecies growing from the germinal layer. |
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| Echinococcus granulosus
(Cestoda: Cyclophyllidea) Note the size and number of segments in this adult tapeworm. There is a scolex, and one immature, one mature, and one gravid proglottid. |
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Card 8:18
| Echinococcus granulosus
(Cestoda: Cyclophyllidea) Numerous hydatid cysts in the liver of a horse. A horse may become infected with a number of cysts at one time (each egg ingested will result in one cyst). |
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| Hydatid cyst
This is the larval stage of Echinococcus granulosus. Note the thick laminated cyst wall and the fibrous host response outside the cyst wall. Also note the daughter cyst with protoscolices within the main cyst. |
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| Diagram of structure associated with the Hydatid Cyst.
(Intermediate stage of Echinococcus granulosus). |
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| Echinococcus multilocularis
(Cestoda: Cyclophyllidea) This animal was infected 9 weeks ago. Note the myriad of small cysts produced by exogenous budding of the mother cysts. |
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| Alveolar hydatid cyst This is the larval stage of Echinococcus multilocularis. Note the thin walls, many protoscolices, and the lack of a host response. |
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| Taenia sp. eggs Thick-shelled, radially striated eggs, light brown in color and measures about 34 X 38 um. |
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| Anoplocephala magna and Anoplocephala perfoliata
(Cestoda: Cyclophyllidea) These tapeworms are found in the small and large intestine (respectively) of the horse. The intermediate hosts are oribatid mites. Note: 1) A. perfoliata is characterized by 4 lappets, one behind each sucker. There are no lappets on A. magna. 2) A. perfoliata is smaller than A. magna. |
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| Moniezia expansa
(Cestoda: Cyclophyllidea) Found in the small intestine of sheep (particularly lambs) and other ruminants. The scolex has 4 prominent suckers and the segments are broader than long. The intermediate host is an orbatid mite in which the cysticercoids develop. |
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| Macracanthorhynchus hiridinaceus
(Phylum: Acanthocephala) Proboscis of the Thorny-Headed worm (Acanthocephala) of pigs. Note the recurved hooks on the proboscis in which assist in the anchoring of the parasite to the intestinal wall. |
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| Macracanthorhynchus hiridinaceus This slide shows the eggs of the thorny-headed worm of pigs. The eggs are thick shelled (4 shells in fact) dark brown, pitted and ellipsoidal. They contain a larval stage, the acanthor. |
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Card 8:27
| 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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