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Korean J Parasitol > Volume 23(2):1985 > Article

Original Article
Korean J Parasitol. 1985 Dec;23(2):203-213. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1985.23.2.203
Copyright © 1985 by The Korean Society for Parasitology
In situ posture of anterior body of Metagonimus yokogawai in experimentally infected dog
Young Kee Jang,Shin Yong Kang,Suk Il Kim and Seung-Yull Cho
Department of Parasitology, College of Medicine, Chung-Ang University, Seoul 151, Korea.

The in situ posture of anterior body of Metagonimus yokogawai was observed in experimental metagonimiasis of dog. The metacercariae were collected from naturally infected sweetfish by peptic digestion; a total of 8 dogs was orally infected with 10,000 metacercariae respectively. Two dogs were killed on 3 days, 9 days, 4 weeks and 10 weeks after the infection. The postures of worms in histological section of small intestine and of whole worms collected from the fixed intestinal mucosa were examined by light and scanning electron microscope. The results were summarized as follows: The recovery rates of worms were 42.6% on 3 days, 55.0% on 9 days, 33.2% on 4 weeks and 9.8% on 10 weeks after the infection respecively. In histological sections of small intesine, most of worms were found at intervillous spaces as ovoid sections of posterior body. However, many worms, especially in 3 day-old worms, revealed protruded anterior body in glandular lumens of crypt. Some sections of anterior body were bifurcated or sacculated. The worms collected from fixed intestinal mucosa under dissecting microscope exhibited a variety of postures. Many worms showed flat shapes with a concavity or curvatures. However, in many worms, the anterior body made a single or multiple protrusions. By SEM observation of protruded anterior body, a longitudinal groove was found. The frequency of worms with protuded anterior body decreased in 9 days, 4 weeks and 10 weeks than in 3 day-old worms. The above findings indicated that the anterior body of juvenile and adult M. yokogawai protruded to lumens of glandular crypt by folding their lateral protions to make a reversible tubelike structure. Frequent multiple protrusions were considered to be made to adapt the microniche of glandular crypts of dog intestine.


Figs. 1-6
Fig. 1. Worm sections of 3 day-old infection of Metagonimus yokogawai. Arrows indicated a sacculated protrusion at the base of main protrusion to glandular lumen of crypt, and a branched section of protrusion (H&E, ×250).

Fig. 2. Another view of 3 day old worm section (H&E, ×250).

Fig. 3. Another view of 3 day old worm sections showing an anterior body sectioned three times (H&E, ×250).

Fig. 4. Three day old worm section with bifurcated protrusion of anterior body (H&E, ×250).

Fig. 5. Transverse section of crypt of Lieberkuehn of small intestinal mucosa in 3 day-old infection. V-shaped, folded section of anterior body was seen. Necrotized enterocytes were also observed (H&E, ×250).

Fig. 6. Worm sections in 4 week-old infection in dog small intestine. Worms located at intervillous spaces (H&E, ×100).

Fig. 7
Figs. 7-1 to 7-36: Unstained, three dimensional M. yokogawai of 3 day-old infection were flattened under cover glass pressure and were photographed (×100).

Figs. 7-1 to 7-8. Worms from intervillous spaces. Worms appeared as conventionally flattened worms.

Fig. 7-12. Ventrally recurved anterior body embraced a villus and was fixed in situ posture.

Figs. 7-9 to 7-18. Anterior body protruded a single projection. The base of the protrusion may be transversely wrinkled.

Figs. 7-19 to Fig. 7-30. Multiple protrusions of anterior body made various shapes of worms.

Figs. 7-31 to 7-36. Prolonged protrusions of anterior body. Sexual organs may be displaced to protruded anterior body in part as in Fig. 7-35.

Fig. 8-13
Figs. 8 to 16. Scanning electron microscopic findings of 3 day-old juvenile worms.

Fig. 8. A main protrusion with a small saccular prominence at side was seen in this worm (×300).

Fig. 9. Magnification of Fig. 8. Longitudinal wrinklings were seen along the axis of protrusion (×1,000).

Fig. 10. Dorsal view of a worm without folding. A protrusion of anterior body was seen (×300).

Fig. 11. A long protrusion of anterior body had daughter protrusions (×300).

Fig. 12. Magnification of Fig. 11 (×800).

Fig. 13. Magnification of Fig. 12. Scale-like tegumental spines at anterior body were seen (×3,000).

Figs. 14-19
Fig. 14. A worm with a small protrusion of anterior body. Multiple transverse wrinklings on posterior body were seen (×200).

Fig. 15. Magnification of Fig. 14. A groove-like folding line was seen at ventral part of the protrusion (×800).

Fig. 16. A folding line was clearly seen in this worm (×600).

Figs. 17 to 19. SEM findings of 4 week-old worms.

Fig. 17. A worm had a small protrusion of anterior body (×200).

Fig. 18. Magnification of Fig. 17, showing two transverse wrinklings (×500).

Fig. 19. A worm with short, multiple protrusions in anterior body (×200).


Table 1
Number of worms collected from intestinal mucosa in dogs infected with 10,000 metacercariae of M. yokogawai

Table 2
Frequency of M. yokogawai with protrusions of anterior body by infection period

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