• Parasites, Hosts and Diseases
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• v.52 no.3
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• pp.273-280
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• 2014

The changing patterns of goblet cell hyperplasia, intestinal epithelial cell turnover, and intestinal motility were studied in ICR and C57BL/6 mice infected with Gymnophalloides seoi (Digenea: Gymnophallidae). Whereas ICR mice retained G. seoi worms until day 7 post-infection (PI), C57BL/6 mice showed a rapid worm expulsion within day 3 PI. Immunosuppression with Depo-Medrol significantly delayed the worm expulsion in C57BL/6 mice. Goblet cell counts were increased in both strains of mice, peaking at day 1 PI in C57BL/6 mice and slowly increasing until day 7 PI in ICR mice. In C57BL/6 mice infected with G. seoi, newly proliferating intestinal epithelial cells were remarkably increased in the crypt, and the increase was the highest at day 1 PI. However, in ICR mice, newly proliferating intestinal epithelial cells increased slowly from day 1 to day 7 PI. Intestinal motility was increased in G. seoi-infected mice, and its chronological pattern was highly correlated with the worm load in both strains of mice. Meanwhile, immunosuppression of C57BL/6 mice abrogated the goblet cell proliferation, reduced the epithelial cell proliferation, and suppressed the intestinal motility. Goblet cell hyperplasia, increased intestinal epithelial cell turnover, and increased intestinal motility should be important mucosal defense mechanisms in G. seoi-infected C57BL/6 mice.

• Parasites, Hosts and Diseases
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• v.57 no.6
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• pp.705-708
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• 2019

Gymnophalloides seoi (Digenea: Gymnophallidae) is a human intestinal trematode contracted by eating raw oysters (Crassostrea gigas) in the Republic of Korea (=Korea). It has been known to be highly endemic in Aphae Island, Shinan-gun, Jeollanam-do (Province). However, recent epidemiological status of G. seoi has not been reported since the 1990s. In this study, we investigated the prevalence of G. seoi metacercariae in natural and cultured oysters collected from 3 islands and 2 coastal areas in western parts of Korea. The oysters were examined using the artificial digestion method followed by stereomicroscopy. The overall positive rate of G. seoi metacercariae in natural oysters was 66.0% (99/150), and the oysters collected from Yubu Island showed the highest infection rate (74.0%). However, the metacercarial density per oyster was relatively low (1.5-2.4 per oyster). By contrast, no metacercaria was found in cultured oysters purchased from 2 coastal areas in Chungcheongnam-do. Thus, we could confirm that natural oysters produced from 3 western coastal islands are infected with G. seoi metacercariae, whereas cultured oysters purchased from 2 coastal areas were free from infection.

• Parasites, Hosts and Diseases
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• v.34 no.4
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• pp.273-278
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• 1996

An epidemiologic survey along the several sites of southern coastal areas of Korean peninsula was performed to know the infection status of Pcnlotremc app. metacercariae in Tapes phiLlppirlawm. The clams were purchased from 13 coastal areas in Kyongsangnam- do alld Chollanam-do. in September, 1990. Each of them was digested with pepsin-HCI solution and examined under a stereomicroscope for the recovery of metacercariae. A total of 232 (77.3%) out of 300 examined clams were proved to have 1 to 273 Pawatrema app. metacercariae (54.7 in average). None of the clams from Samoan-myon Kosong-gun and Dolsan-up. Yochon-gun was infected with metacercariae. However, all of the clams from Yonghyon-myon, Sachon-guu, Dohwa-myon, Kohung-gun, Ahllyang-myon. Changhung- gun and Chiryang-myon. Kangiin-gun were infected with average 71, 31, 80 and 42 metacercariae respectively. Of the clams from Kohyon-myon, Namhae-gun, Doam-myon, Kangiin-gun and Kusan-myon. Uichang-guil examined, 97.5%. 95.0% and 90.0% were infected with about 117. 76 and 28 metacercariae. In other 4 surveyed areas. Seolchon rlyoll, Namhae-gun, Hwayang-myon. Yochon-gun Byollyang-myon, Sungju-gun and Bukpyong-myon, Haenam-gun. 55.0%-80.0% of clams were positive. and their average intensity of infection ranged from 6 to 25 metacercariae. From these results, it was confirmed that Tcpes philippincrum from southern coastal areas of Korea are highly infected by Parvatrema spp. metacercariae.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.154-159
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• 1983

A Gymnophallid cercaria was found in the gonadal tissue of Tapes philippinarum, and was described as a new species, Cercaria tapes n. sp. The host clams were collected from the intertidal zone of Seo-myon, Seo-chon gun, Korea from September 1980 to August 1981. The size of sporocysts was $380-650{\times}130-160{\mu}m$. The anterior part of the cercaria bears a subterminal opening and pharynx. The sporocyst bears ca. 30 cercariae and germ balls. The cercaria is elliptical in shape. The dimension of body is $160-187{\times}62-77{\mu}m$. the tail stem is $47-52{\times}17{\mu}m$, and the tail furcae is $67-72{\times}12-15{\mu}m$. Excretory bladder is Y-shaped, and the flame cell formula is 2(1)+(1)=4. The infection rate of the cercaria to the host clam was $2.01\%$ (42 infected/2,086 short-necked clams observed). The highest infection rate ($5.74\%$) was found in March, and the lowest one ($0.4\%$) observed in January. No infection was detected in May and June. The infection rates varied with the size of the short-necked clam. It was the clams of host of 2.1-3.0 cm, 3.1-4.0 cm and 4.1-5.0 cm in shell length are $0.38\%,\;15.3\%$ and $0.09\%$ respectively. The cercaria was not observed in the specimens smaller than 2.0 cm in shell length.

• Parasites, Hosts and Diseases
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• v.33 no.3
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• pp.165-172
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• 1995

A transmission electron microscopic study was performed on the ultrastructure of the tegumental layer of GymophoLloines seoi (Digenea: Gymnophallidae) metacercarlae and adults. The metacercariae were obtained from naturally infected oysters, Crcssosoea gigas, and the adults from experimentally infected C3H mice. The tegumental layer generally revealed a small number of foldings, numerous small vacuoles, sines, and muscle bundles. Beneath the muscle layer, nuclei of the tegumental cells were located. There was little difference in the structure of the tegument between the metacercariae and adults. The oral sucker, having well-developed muscle layers, showed a similar structure to the ventral sucker except numerous foldlngs in the ventral sucker. The ventral pit was surrounded by a thin spcpiu layer, where a number of microtubules and mitochondria were seen. Around the ventral pit located well-developed circular and longitudinal muscles. The results showed that the ultrastructure of the tegumental layer of G. seoi metacercariae and adults revealed little difference from other trematodes in general. The ventral pit, a peculiar structure of this trematode, seems to function as a sphincter or an accessory adhesive organ.