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Korean J Parasitol > Volume 23(1):1985 > Article

Original Article
Korean J Parasitol. 1985 Jun;23(1):47-57. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1985.23.1.47
Copyright © 1985 by The Korean Society for Parasitology
Studies on intestinal trematodes in Korea XIX. Light and scanning electron microscopy of Fibricola seoulensis collected from albino rats treated with praziquantel
Byong Seol Seo,In June Cha,Jong Yil Chai,Sung Jong Hong and Soon Hyung Lee
Department of Parasitology and Institute of Endemic Deseases, College of Medicine, Seoul National University, Seoul 110, Korea.

An experimental study was performed to observe the in vivo effects of praziquantel on the light and scanning electron microscopic morphology of Fibricola seoulensis. The metacercariae were obtained from the snakes and 1,000 in each number was orally given to total 15 albino rats; 5 controls and 10 treatment group. Seven days later the 10 rats were treated with 10 mg/kg praziquantel and sacrificed 1-24 hours later to search for the worms from their small intestines. The major light microscopic changes in the drug-exposed worms were early contraction followed by relaxation of especially their forebody, vacuolization of the tegument and subtegumental parechymal layers, and narrowing of the intestinal lumens. The scanning electron microscopic findings were characterized by formation of numerous blebs followed by rupture and subsequent destruction of their whole tegument. These results show that the change in worm body is not confined to the tegument but extends to deeper parechymal portions and also occurs in their intestines. It is suggested that the drug uptake by the worms should be either through their tegument or through the digestive tract.


Fig. 1
Changes in size of F. seoulensis after exposure to praziquantel in vivo.

Figs. 2-5
Fig. 2. A normal adult worm of F. seoulensis showing its characteristic feature. Acetocarmine stain (scale: 0.1mm).

Fig. 3. Two drug-exposed specimens (6-hour group). The forebody is contracted while the hindbody elongated.The lateral margins show hazy appearance (arrow heads) due to severe vacuolizations. Acetocarmine stain (scale: 0.2mm).

Fig. 4. The laateral margin of a worm (24-hour group). The tegument is markedly destroyed and many vacuoles are seen in the superficial and deep layers (scale: 0.1mm).

Fig. 5. Another worm (24-hour group) showing many parenchymal vacuoles (scale: 25µm).

Figs. 6-9
Fig. 6. A sectioned worm of 6-hour group. The lateral margins of the forebody show many vacuoles (arrow heads). H-E stain (scale: 0.1mm).

Fig. 7.Ibid, 24-hour group. The vacuolization of the parenchymal tissues is conspicuous. H-E stain (scale: 25µm).

Fig. 8. Cross section of a control worm showing two intact intestines (arrow heads) with wide lumens and thin walls. H-E stain (scale: 25µm).

Fig. 9. Section of the drug-exposed worms (a: 6-hour group, b: 24-hour group) showing their nearly occluded intestinal lumen and thickened wall. H-E stain (scale: 25µm).

Figs. 10-13
Fig. 10. Scanning electron microscopic view of the lateral margin of a drug-exposed worm (1-hour group).Many tegumental blebs are seen (arrow heads) and the tegumental architecture is severely altered (scale: 35µm).

Fig. 11. Magnification of an arrow portion of Fig. 10. The tegumental blebs are much variable in size and shape (scale: 4µm).

Fig. 12. The tegumental surface of the hindbody of a not severely damaged worm (6-hour group). Many blebs are seen and the cobblestone-like tegumental integrity is a little deformed (scale: 2.5µm).

Fig. 13. The tegument around oral sucker of a drug-exposed worm (1-hour group). The ruptured blebs (arrow heads) are seen but the spines are entirely intact (scale: 4µm).

Figs. 14-17
Fig. 14. Another worm in the same group as Fig. 13, showing the tegument between oral and ventral suckers. Despite the bleb formation (large arrows) on the tegument, the sensory papillae appear to be intact (small arrow heads). The blebs and the sensory papillae grossly have no relations each other (scale: 5µm).

Fig. 15. The forebody of a drug-exposed dead worm (6-hour group) recovered from the caecum of a rat. The whole tegumental surface is severely destroyed (scale:33µm).

Fig. 16. Magnification of the worm in Fig. 15. There is no recognizable tegumental structures such as the spines, sensory papillae, etc. (scale: 4µm).

Fig. 17.Ibid, another portion. The tegumental surface shows much rough and dirty appearance (scale 4µm).

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