The tegumental ultrastructure of juvenile and adult Echinostoma cinetorchis (Trematoda: Echinostomatidae) was observed by scanning electron microscopy. Three-day (juvenile) and 16-day (adult) worms were harvested from rats (Sprague-Dawley) experimentally fed the metacercariae from the laboratory-infected fresh water snail, Hippeutis cantori. The worms were fixed with 2.5% glutaraldehyde, processed routinely, and observed by an ISI Korea DS-130 scanning electron microscope. The 3-day old juvenile worms were elongated and ventrally curved, with their ventral sucker near the anterior two-fifths of the body. The head crown was bearing 37-38 collar spines arranged in a zigzag pattern. The lips of the oral and ventral suckers had 8 and 5 type II sensory papillae respectively, and between the spines, a few type III papillae were observed. Tongue or spade-shape spines were distributed anteriorly to the ventral sucker, whereas peg-like spines were distributed posteriorly and became sparse toward the posterior body. The spines of the dorsal surface were similar to those of the ventral surface. The 16-day old adults were leaf-like, and their oral and ventral suckers were located very closely. Aspinous head crown, oral and ventral suckers had type II and type III sensory papillae, and numerous type I papillae were distributed on the tegument anterior to the ventral sucker. Scale-like spines, with broad base and round tip, were distributed densely on the tegument anterior to the ventral sucker but they became sparse posteriorly. At the dorsal surface, spines were observed at times only at the anterior body. The results showed that the tegument of E. cinetorchis is similar to that of other echinostomes, but differs in the number and arrangement of collar spines, shape and distribution of tegumenal spines, and type and distribution of sensory papillae.
Figs. 1-5 Fig. 1. Ventral view of a 3-day old juvenile worm of E. cinetorchis (×370).
Fig. 2. Head crown of a 3-day old worm with its oral sucker(CS) and collar spines (arrow heads) (×1,010).
Fig. 3. The ventral sucker of a 3-day old worm showing type II sensory papillae on its lip (×1,020).
Fig. 4. Tegument of ventral surface anterior to the ventral sucker (3-day worm). Tongue of spade-shape apincs and type III sensory papillae (arrow head) are seen (×4,060).
Fig. 5. Tegument of ventral surface posterior to the ventral sucker (30day worm), showing peg-like spines (×4,060).
*Bar unit: µm.
Figs. 6-11 Fig. 6. Velvety tegument of ventro-posterior region of a 3-day worm (×10,200).
Fig. 7. Tegument of dorsal surface anterior to the ventral sucker (3-day worm), showing tongue or spade-shape spines (×4,050).
Fig. 8. Tegument of dorso-median region (3-day worm), showing peg-like spines distributed sparesly (×4,050).
Fig. 9. Tegument of dorsal posterior one-third region (3-day worm), showing nearly no spines (×4,050).
Fig. 10. Tegument of posterior extremity (3-day worm), showing nearly no spines (×10,200).
Fig. 11. Ventral view of a 16-day old adult specimen of E. cinetorchis (×20.4).
*Bar unit: µm.
Figs. 12-17 Fig. 12. Head crown of a 16-day worm, showing collar spines retracted from the tegumental surface (×306).
Fig. 13. Head crown (3-day worm) with protruded collar spines, for comparison with Fig. 12(×830).
Fig. 14. Dorsal view of the head crown (3-day worm), showing partially protruded collar spines (arrow heads) (×2,030).
Fig. 15. Tegument of ventral surface anterior to the ventral sucker (16-day worm), showing scale-like spines and type I sensory papillae (×2,040).
Fig. 16. Another portion, where the spines are retracted from the tegumental surface (×3,060).
Fig. 17. Tegument of ventro-lateral region between the head crown and ventral sucker (16-day worm), where 1~4 groups of type I papillae are scatteredly seen (×1,020).
*Bar unit: µm.
Figs. 18-22 Fig. 18. Ventral sucker, cirrus (C) and genital opening (GO), a 16-day worm (×407).
Fig. 19. Lip of the ventral sucker (16-day worm), showing the wrinkled tegument and many type III sensory papillae(×1,530).
Fig. 20. Tegument of ventro-posterior region of a 16-day worm. The tegument became smooth and the spines are distributed very sparsely (×800).
Fig. 21. Tegument of corso-anterior region (16-day worm), showing velvety cytoplasmic processes with few spines (×3,060).
Fig. 22. Tegument of dorso-posterior region (16-day worm), showing porous and cobblestone-like tegumental surface (×6,020).
*Bar unit: µm.
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