Research notes MURRAY, M., JARRETT, W. F. H. and JENNINGS, F. W. (1971a) Mast cells and macro-molecular leak in intestinal immunological reactions. The influence of sex of rats infected with Nippostrongylus brasiliensis. Immunology, 21, 17-31. MURRAY, M., MILLER, H. R. P., SANFORD, J. and JARRETT, W. F. H. (1971b) 5-hydroxy tryptamine in intestinal immunological reactions. Its relationship to mast cells activity and worm expulsion in rats infected with Nippostrongylus brasiliensis. International Archives of Allergy and Applied Immunology, 40, 236-247. SEN, H. G., JOSHI, U. N. and SETH, D. (1965) Effect of cortisone upon Ancylostoma caninum infection in albino mice. Transactions of the Royal Society of Tropical Medicine and Hygiene, 59, 684-689. STEEL, R. G. D. and TORRIE, J. N. (1967) Principles and procedures of Statistics. McGraw-Hill: New York. TALIAFERRO, W. H. and SARLES, M. P. (1939) The cellular reactions in the skin, lungs and intestine of normal and immune rats after infection with Nippostrongylus muris. Journal of Infectious Diseases, 64, 157-192. VARDHANI, V. and JOHRI, G. N. (1978) Pharmacological estimation of histamine in the intestine of mice experimentally infected with single doses of Ancylostoma caninum larvae. Journal of Hygiene, Epidemiology Microbiology and Immunology (In press)., WELLS, P. D. (1962) Mast cell, eosinophil and histamine levels in Nippostrongylus brasiliensis infected rats. Experimental Parasitology, 12, 82-101. Accepted 17 February, 1978.
Journal ofHclminlhology (1979) 53, 39-40
RESEARCH NOTE Abnormal growth pattern of Diphyllobothrium dendriticum in rainbow trout KARIN ANDERSEN University of Oslo, Zoological Museum, Sars gt. 1, Oslo 5, Norway In order to have access to Diphyllobothrium dendriticum (Nitzsch, 1824) plerocercoids throughout the year we transfer larvae from naturally infected salmonids to rainbow trout (Salmo gairdnieri), keep the latter in aquaria (water temperature 4-8°C) and feed them on commercial diet in pellet form until living larvae are needed for infections. The rainbow trout (20-25 cm long) are bought from a fish farm near Oslo and hitherto n o helminth infection has ever been observed in any of them. The plerocercoids are, together with 1-2 ml saline, injected into the abdominal cavity of the new host. This has proved to be quite successful and 50-60 % of the plerocercoids manage to reestablish and reencyst in their new host. Even after a period of 2\ years (this is the longest period hitherto experienced) the larvae were alive, had a " n o r m a l " appearance and were infective to definitive hosts. Two years ago 2 rainbow trout were each injected with about 10 pieces (10-15 m m long) of D. dendriticum plerocercoids. The scolex and anterior region as well as the posterior region of the plerocercoids had been removed. The fishes were kept in an aquarium under the same conditions as mentioned above. One fish died 22 months later, while the other was killed the day after the first one died. When the fishes were autopsied one (the fish which had died) harboured 6 and the other 3 big (from 6-10 m m in diameter) translucent 39
Research Notes
cysts located in the body cavity; each cyst harboured one extremely long and slender piece of a D. dendriticum larva. These "giant" pieces were alive when kept in saline. They appeared, however, very relaxed with a smooth outer surface covered with short microtriches. In contrast to intact D. dendriticum larvae they contracted only very little when killed and fixed in 4% formalin in 1 % saline (Figs. 1-4). The small pieces of D. dendriticum plerocercoids (10-15 mm long when alive) injected nearly two years earlier had developed into very long and slender plerocercoid pieces (from 152 to 310 mm long when killed and fixed in formol saline) without, however, regenerating a scolex, developing segmentation or primordia. The latter is usual in "normal" plerocercoids in trout when the larvae reach a certain size (Vik, 1957). The increase in length cannot just be explained by stretching of the pieces injected 22 months earlier but must to some extent also be due to growth. Intact larvae usually increase from 3 to 5 times in length when totally relaxed and killed in tapwater. The plerocercoid pieces in rainbow trout had, however, during a period of 22 months, increased between 10 and 30 times in length. When sectioned (Fig. 2) the plerocercoid pieces from rainbow trout were histologically similar to cross sections through tapwater-killed small D. dendriticum larvae (Halvorsen, 1970—Figs. 32 and 38). In tapwater-killed specimens, however, the epidermis is damaged due to the killing method. 10 control fish which had not been used in any experiment were absolutely free of helminths. The cellular composition of plerocercoids of D. dendriticum has been worked out by Bonsdorff et al. (1971). It is further known that the cell composition in the anterior neck region of adults is very similar to that in plerocercoids (Wikgren et al., 1971). In adult worms all growth and differentiation is believed to take place in the neck region (Wikgren, 1971). Smyth (1959) partly succeeded in cultivating small fragments of D. dendriticum larvae in vitro. These fragments formed "miniature" proglottids and developed in complete genital sets. The exact pattern and mechanism behind growth in pseudophyllidean cestodes (larvae as well as adults) is still unsolved and requires further studies. The present experiment, however, supports the idea that growth and differentiation is controlled from the scolex or neck region and if this is removed we can under certain conditions achieve an uncontrolled growth and abnormal development. ACKNOWLEDGEMENT I am grateful to Professor Rolf Vik for the research facilities made available to me at the Zoological Museum.
REFERENCES BONSDORFF, C. -H. von, FORSSTEN, T., GUSTAFSSON, M. K. S. and WIKGREN, B. -J. (1971) Cellular composition of plerocercoids of Diphyllobothrium dendriticum (Cestoda). Ada Zoologica Fennica, 132, 1-25. HALVORSEN, O. (1970) Studies of the helminth fauna of Norway XV: On the taxonomy and biology of plerocercoids of Diphyllobothrium Cobbold, 1858 (Cestoda, Pseudophyllidea) from North-western Europe. Nytt Magasin for Zoology, 18, 113-174. SMYTH, J. D. (1959) Maturation of larval pseudophyllidean cestodes and strigeid trematodes under axenic conditions: the significance of nutritional levels in platyhelminth development. Annals of New York Academy of Sciences, 11, 102-125. VIK, R. (1957) Studies of the helminth fauna of Norway, I: Taxonomy and ecology of Diphyllobothrium norvegicum n. sp. and the plerocercoid of Diphyllobothrium latum (L.). Nvtt Magasin for Zoology, 5, 25-93. WIKGREN, B. -J. (1971) Anpassningsfenomen hos parasitter. Tiedoksianto-Information, 12, 3-9. WIKGREN, B. -J., GUSTAFSSON, M. K. S. and KNUTS, G. M. (1971) Primary anlage formation in diphyllobothriid Tapeworms. Zeitschrift fur Parasitenkunde, 36, 131-139. Accepted 10 February, 1978. 40
FIG. 1. S.E.M. picture of a "piece" of D. dendriticum larva developed in rainbow trout, killed and fixed in formolsaline; FIG. 2. Cross section of a "piece" of D. dentriticum larva developed in rainbow trout, killed and fixed in formolsaline. e = epidermis, ex = excretory vessel, p = parenchyma! longitudinal musculature; FIG. 3. The surface topography of a normal transplanted D. dendriticum larva, killed and fixed in formolsaline; FIG. 4. Cross section of a normal transplanted D. dendriticum larva, killed and fixed in formolsaline.
Journal ofHclminlhology (1979) 53, 39-40
RESEARCH NOTE Abnormal growth pattern of Diphyllobothrium dendriticum in rainbow trout KARIN ANDERSEN University of Oslo, Zoological Museum, Sars gt. 1, Oslo 5, Norway In order to have access to Diphyllobothrium dendriticum (Nitzsch, 1824) plerocercoids throughout the year we transfer larvae from naturally infected salmonids to rainbow trout (Salmo gairdnieri), keep the latter in aquaria (water temperature 4-8°C) and feed them on commercial diet in pellet form until living larvae are needed for infections. The rainbow trout (20-25 cm long) are bought from a fish farm near Oslo and hitherto n o helminth infection has ever been observed in any of them. The plerocercoids are, together with 1-2 ml saline, injected into the abdominal cavity of the new host. This has proved to be quite successful and 50-60 % of the plerocercoids manage to reestablish and reencyst in their new host. Even after a period of 2\ years (this is the longest period hitherto experienced) the larvae were alive, had a " n o r m a l " appearance and were infective to definitive hosts. Two years ago 2 rainbow trout were each injected with about 10 pieces (10-15 m m long) of D. dendriticum plerocercoids. The scolex and anterior region as well as the posterior region of the plerocercoids had been removed. The fishes were kept in an aquarium under the same conditions as mentioned above. One fish died 22 months later, while the other was killed the day after the first one died. When the fishes were autopsied one (the fish which had died) harboured 6 and the other 3 big (from 6-10 m m in diameter) translucent 39
Research Notes
cysts located in the body cavity; each cyst harboured one extremely long and slender piece of a D. dendriticum larva. These "giant" pieces were alive when kept in saline. They appeared, however, very relaxed with a smooth outer surface covered with short microtriches. In contrast to intact D. dendriticum larvae they contracted only very little when killed and fixed in 4% formalin in 1 % saline (Figs. 1-4). The small pieces of D. dendriticum plerocercoids (10-15 mm long when alive) injected nearly two years earlier had developed into very long and slender plerocercoid pieces (from 152 to 310 mm long when killed and fixed in formol saline) without, however, regenerating a scolex, developing segmentation or primordia. The latter is usual in "normal" plerocercoids in trout when the larvae reach a certain size (Vik, 1957). The increase in length cannot just be explained by stretching of the pieces injected 22 months earlier but must to some extent also be due to growth. Intact larvae usually increase from 3 to 5 times in length when totally relaxed and killed in tapwater. The plerocercoid pieces in rainbow trout had, however, during a period of 22 months, increased between 10 and 30 times in length. When sectioned (Fig. 2) the plerocercoid pieces from rainbow trout were histologically similar to cross sections through tapwater-killed small D. dendriticum larvae (Halvorsen, 1970—Figs. 32 and 38). In tapwater-killed specimens, however, the epidermis is damaged due to the killing method. 10 control fish which had not been used in any experiment were absolutely free of helminths. The cellular composition of plerocercoids of D. dendriticum has been worked out by Bonsdorff et al. (1971). It is further known that the cell composition in the anterior neck region of adults is very similar to that in plerocercoids (Wikgren et al., 1971). In adult worms all growth and differentiation is believed to take place in the neck region (Wikgren, 1971). Smyth (1959) partly succeeded in cultivating small fragments of D. dendriticum larvae in vitro. These fragments formed "miniature" proglottids and developed in complete genital sets. The exact pattern and mechanism behind growth in pseudophyllidean cestodes (larvae as well as adults) is still unsolved and requires further studies. The present experiment, however, supports the idea that growth and differentiation is controlled from the scolex or neck region and if this is removed we can under certain conditions achieve an uncontrolled growth and abnormal development. ACKNOWLEDGEMENT I am grateful to Professor Rolf Vik for the research facilities made available to me at the Zoological Museum.
REFERENCES BONSDORFF, C. -H. von, FORSSTEN, T., GUSTAFSSON, M. K. S. and WIKGREN, B. -J. (1971) Cellular composition of plerocercoids of Diphyllobothrium dendriticum (Cestoda). Ada Zoologica Fennica, 132, 1-25. HALVORSEN, O. (1970) Studies of the helminth fauna of Norway XV: On the taxonomy and biology of plerocercoids of Diphyllobothrium Cobbold, 1858 (Cestoda, Pseudophyllidea) from North-western Europe. Nytt Magasin for Zoology, 18, 113-174. SMYTH, J. D. (1959) Maturation of larval pseudophyllidean cestodes and strigeid trematodes under axenic conditions: the significance of nutritional levels in platyhelminth development. Annals of New York Academy of Sciences, 11, 102-125. VIK, R. (1957) Studies of the helminth fauna of Norway, I: Taxonomy and ecology of Diphyllobothrium norvegicum n. sp. and the plerocercoid of Diphyllobothrium latum (L.). Nvtt Magasin for Zoology, 5, 25-93. WIKGREN, B. -J. (1971) Anpassningsfenomen hos parasitter. Tiedoksianto-Information, 12, 3-9. WIKGREN, B. -J., GUSTAFSSON, M. K. S. and KNUTS, G. M. (1971) Primary anlage formation in diphyllobothriid Tapeworms. Zeitschrift fur Parasitenkunde, 36, 131-139. Accepted 10 February, 1978. 40
FIG. 1. S.E.M. picture of a "piece" of D. dendriticum larva developed in rainbow trout, killed and fixed in formolsaline; FIG. 2. Cross section of a "piece" of D. dentriticum larva developed in rainbow trout, killed and fixed in formolsaline. e = epidermis, ex = excretory vessel, p = parenchyma! longitudinal musculature; FIG. 3. The surface topography of a normal transplanted D. dendriticum larva, killed and fixed in formolsaline; FIG. 4. Cross section of a normal transplanted D. dendriticum larva, killed and fixed in formolsaline.
![Leucocyte migration in rainbow trout (Oncorhynchus mykiss [Walbaum]): optimization of migration conditions and responses to host and pathogen (Diphyllobothrium dendriticum [Nitzsch]) derived chemoattractants.](/assets/img/hold.png)
