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| ORIGINAL ARTICLE |
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| Year : 2015 | Volume
: 6
| Issue : 1 | Page : 38-43 |
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Histopathological alterations in the vital organs of Indian Major Carps with parasitic infestation in fish farms West Bengal, India
Kurva Raghu Ramudu, Gadadhar Dash
Department of Aquatic Animal Health, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
| Date of Web Publication | 8-Jan-2015 |
Correspondence Address:
Kurva Raghu Ramudu
Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, 5, Budherhat Road, Chakgaria, Kolkata - 700 094, West Bengal
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/2394-2002.148893
The study was conducted to investigate the histological changes of vital organs such as kidney, gills and brain with the mixed infestation of parasites in Indian Major Carps (IMC). The parasites such as Myxobolus spp., Thelohanellus spp., Trichodina spp., Dactylogyrus spp., Gyrodactylus spp. and Nematodes were observed in three IMC. Several histological alterations were observed in the kidney of Catla catla, Labeo rohita and Cirrhinus mrigala, which includes vacuolar degeneration in the epithelium of renal tubules, focal areas of necrosis, proliferation of bowman's capsule and many cases the renal tubules lost its shape and canalculi formation was observed. The gills showed focal areas of necrosis, exacerbated swelling of gill arch, deposition of distinct black melanin pigmentation at the basal point of the gill arch, loss of primary and secondary lamellae, prominent vacuolar degeneration and formation of vacuoles. The presence of protozoan parasites in brain tissue resulted necrosis of the brain tissue, black pigmentation, vacuolization of myelin sheath of nerve fibers and common degenerative changes. Aims: To study histological changes of vital organs such as kidney, gills and brain with the mixed infestation of parasites in Indian Major Carps (IMC). Settings and Design: The organs fixed in 4% formalin are transferred to 50% ethyl alcohol and stored for further analysis. Materials and Methods: Histopathological analysis was made as described by Roberts. Statistical Analysis Used: Nil. Results: Described in text. Conclusions: The present study brings about conclusion that impact of mixed infestation of the parasites on their hosts was severe. Histopathological changes were observed in vital organs which might be due to toxins released by different parasites or physical damage of tissue with the presence of parasites. Keywords: Histological alterations, Indian major carps, vital organs
How to cite this article:
Ramudu KR, Dash G. Histopathological alterations in the vital organs of Indian Major Carps with parasitic infestation in fish farms West Bengal, India. Drug Dev Ther 2015;6:38-43 |
How to cite this URL:
Ramudu KR, Dash G. Histopathological alterations in the vital organs of Indian Major Carps with parasitic infestation in fish farms West Bengal, India. Drug Dev Ther [serial online] 2015 [cited 2019 Apr 21];6:38-43. Available from: http://www.ddtjournal.org/text.asp?2015/6/1/38/148893 |
| Introduction | |  |
The Indian major carps, namely Catla catla, Labeo rohita and Cirrhinus mrigala contribute as much as 87% of total fresh water aquaculture production. Parasitic infestations, especially ectoparasites like protozoans, monogenetic and digenetic flukes are the most devastating groups affecting skin and gills that induces sliminess of the skin, irritation, destruction of gills, anorexia and impaired breathing (Lom [1] and Abbas et al. [2] ). The synergistic action of the parasites may cause mortalities (Abbas et al., [2] Osman [3] ) Ectoparasitic ciliates are the most common parasites found in fishes (Lom and Dykova [4] ). Trichodina spp. as well as Chilodonella spp. causes 70% mortality among 2-months old fry of cultured grass carp (Uzbilek and Yilidiz [5] ). Trichodina spp. glides rapidly over the gills and skin, affects all fish species causing direct or indirect death (Durborow). [6] Trichodinids commonly occur in association with other ectoparasites, especially, monogenic and digenic flukes (Pearse). [7] Monogenetic flukes are a group of parasites best described as flatworms commonly found on the gills, skin or fins of fishes have a series of hooks that attach to the fish causing irritation, excessive mucus production (Reed et al.[8] and Soulsby [9] ). Severe infestation of monogenean flukes may cause dyspnea and die of condition of cultivable fishes (Moeller). [10] Digenetic trematodes require several hosts to complete their life cycle. The majority of digenetic trematodes that infect fish by metacercaria larvae or "grub" stage (Bowser). [11] Metacercarial larval infestation in fish causes economic losses to the farmers due to mass mortality (Paperna). [12]
It is important to mention here that the parasitic infestations were reportedly playing a major role in disease occurrences (78%) in Indian freshwater aquaculture (Lakra). [13] Scientist reported that ectoparasitic diseases are the main problem in freshwater fish farms of Andhra Pradesh (Mohan et al.). [14] The freshwater fish farmers of Andhra Pradesh, India (Vineetha and Abraham [15] ) and West Bengal, India (Sil et al.) [16] were estimated to produce about 21% and 26% less, respectively than the expected production due to diseases, poor farm management practices and impaired growth. It is important to mention here that parasitic infestations caused stress at initial stages then followed by mortalities. So it is very important to study parasitic infestations and histological changes in vital organs of parasitized fishes. Histological alterations used as indicators for entire health of overall population in the ecosystem. The objectives of present work was to study the histological changes of vital organs such as kidney, gills and brain due to mixed infestation of parasites in Indian major carps (IMC).
| Materials and Methods | | |
The samples of (Catla catla, Labeo rohita and Cirrhinus mrigala) were collected in live condition and brought to the laboratory with water filled buckets. Vital organs like kidney, gill and brain were thoroughly observed under microscope for the presence of parasites. These organs were infested by different parasites such as Myxobolus spp., Trichodina spp., Thelohanellus spp., Dactylogyrus spp. and Gyrodactylus spp. Vital organs from these naturally infested fishes were taken for histopathological observations.
The vital organs were fixed in 4% formalin, transferred to 50% ethyl alcohol and stored for further analysis. Histopathological analysis was made as described by Roberts. [17] The sections were screened and color microphotographs were taken from the selected slides at different magnifications with the help of binocular phase contrast microscope with in-built digital camera and attached monitor (Motic: Model BA400).
| Results and Discussion | | |
The vital organs were infested by different parasites like Myxobolus spp., Trichodina spp., Thelohanellus spp., Dactylogyrus spp. and Gyrodactylus spp., showed in [Figure 1]a-f. These parasites caused internal damage to the tissues of different organs. All the major organs like kidney, gill, brain and muscle were thoroughly studied under microscope for histopathological changes.  | Figure 1: (a) Cyst of Myxobolus spp. (arrow) present in the gills of Catla catla (b) Cyst of Myxobolus spp. (arrows) present on the caudal fin of Labeo rohita (c) Trichodina sp. present on the skin of Labeo rohita (Wet mount, 20x) (d) Two different Thelohanellus spp. from the gills of IMC, and with clear long polar filament (arrows) (Giemsa stained, 20x) (e) Magnified view of Dactylogyrus sp. present in the gills with clear anchor, (arrow) of IMC (Wet mount, 20x) (f) Gyrodactylus sp. with clear attachment site (arrow) and attached to the body of IMC (Wet mount, 10x)
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Kidney
Kidney is a target organ in many diseases due to the affinity of the organ for circulating particulate antigens. Yu and Wu [18] observed severe lesion of the glomeruli capsules and fat deposits on the kidney tubules of Hypophthalmicthys molitrix.
In the present study the kidney of the Catla catla showed distinct black melanin pigmentation, necrosis of nephric tubules and vacuole formation [Figure 2]a and hind kidney showing enlargement of bowman capsule [Figure 2]b. The necrosis of the renal tubules affects the metabolic activities and promotes metabolic abnormalities in fish (Yokote), [19] which was similar with the present observations.  | Figure 2: (a) The kidney of the Catla catla showing distinct black melanin pigmentation (yellow arrow), necrosis of nephric tubules was also evident (light blue arrow) and vacuole formation (green arrow) at some places (H&E, 40x) (b) The kidney of the Catla catla showing distinct black melanin pigmentation (yellow arrow), prominent vacuole formation (green arrow) in some places and enlargement of bowman capsule (pink arrow) (H&E, 40x) (c) The kidney of Labeo rohita showing the prominent circular vacuolar spaces filled with damaged cells (blue arrow) and necrosis of the kidney tissue (light blue arrow) observed. The nephric tubules showed distinct interstitial spaces (red arrow) (H&E, 100x) (d) The kidney of Labeo rohita showing proliferation of bowman capsule (pink arrow) and many cases the renal tubules lost its shape (yellow arrow), (H&E, 100x) (e) The kidney of Cirrhinus mrigala showing black pigmentation (yellow arrow) and distinct vacuole formation (green arrow) normal structure of renal tubules were lost (H&E, 40x) (f) The kidney of Cirrhinus mrigala showing distinct canalculi within the tissue (red arrow) and in some places few black pigments (yellow arrow) were observed (H&E, 40x)
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The head kidney of Labeo rohita showed the prominent circular vacuolar spaces filled with damaged cells, necrosis of the tissue. The nephric tubules showed distinct interstitial spaces [Figure 2]c. Enzootic nature of myxosporidians in Indian Major Carps causing degenerative and necrotic changes in the kidney tubules have been described by Mishra et al., [20] which was similar with present study. The hind kidney showing proliferation of Bowman's capsule and many a cases the renal tubules were deshaped [Figure 2]d.
The head kidney of Cirrhinus mrigala showed black pigmentation and distinct vacuole formation and normal structure of renal tubules were lost [Figure 2]e. The hind kidney showed distinct canalculi formation within the tissue. Canalculi formation may be due to toxins released by parasites or exposure of kidney to lethal concentrations of the toxins which showed enlargement, vacuolar degeneration, necrosis of cells that corroborated with the works of Gupta and Dalela, [21] Csepai, [22] Konar and Hazards, [23] Bakthavathsalam et al., [24] Duable and Shah, [25] Rashatwar et al.[26] and Perisetti. [27] The vacuolar spaces in top corner being occupied by damaged mass of the cells and the normal shape of renal tubules were not observed [Figure 2]f.{Figure 2}
Gills
Gills of Catla catla showed exacerbated swelling of gill arch with complete loss of primary and secondary lamellae which was similar to the works of Dey et al. [28] The arch swelled maximum at middle point compare to basal and proximal point [Figure 3]a. At high magnification, gill tissue showed the exacerbated swelling of gill arch which was similar to the reports of Ghosh et al.[29] and Sanaullah and Ahmed. [30] Depositions of distinct black melanin pigmentation at the basal point of the gill arch were also observed [Figure 3]b. In the present study mixed infestation of parasites were found in the gills. The gill cells respond to the parasites with abnormal production of mucus, also epithelial hyperplasia was observed.  | Figure 3: (a) Gill of Catla catla showing the exacerbated swelling of gill filament (blue arrow) with complete loss of primary and secondary lamellae. The arch swelled maximum at middle point compare to basal and proximal point (H&E, 40x) (b) High magnification of the gill tissue of Catla catla showing the exacerbated swelling of gill filament (blue arrow), deposition of distinct black melanin pigmentation (yellow arrow) at the basal point of the gill arch is one of the feature of the present slide. (H&E, 100x) (c) The gill of the Labeo rohita showing excessive proliferation of gill arch with massive loss of primary and secondary lamellae (orange arrow), the arch shown granulation and vacuoles (light green arrow) (H&E, 40x) (d) High magnifications the gill of the Labeo rohita showing excessive proliferation of gill arch (black arrow) with complete loss of primary and secondary lamellae, prominent vacuolar degeneration were also observed (H&E, 100x) (e) The gill of the Cirrhinus mrigala showing complete degeneration of gill arch (orange arrow), damage of gill arch to very high degree leading to the formation of vacuoles (blue arrow) (H&E, 40x) (f) The gill of the Cirrhinus mrigala showing degeneration and necrosis of arch (light blue arrow) leading to the formation of vacuum space (yellow arrow) (H&E, 40x)
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The gill of the Labeo rohita showing excessive proliferation of gill arch with massive loss of primary and secondary lamellae and the arch showed granulation and vacuoles. The symmetry of arrangement of primary lamellae has been lost, inter digitations were damaged prominently [Figure 3]c. Due to heavy infestation of parasites the gill structures were totally damaged and the swelling might be due to the presence of toxins released by the parasites or pollutants which supported by works of Ramudu and Dash [31] and Perisetti, [27] respectively. High magnifications of the gill showed excessive proliferation of gill arch with complete loss of primary and secondary lamellae, prominent vacuolar degeneration [Figure 3]d, which were similar with results as found in Catla catla (Dey et al).[28]
The gills of the Cirrhinus mrigala showed complete degeneration of gill arch with excessive proliferation of primary lamellae. Similar abnormalities in the gills were observed in fishes exposed to miscellaneous pesticides (Lowe, [32] Eller, [33] Jauch, [34] Nowak, [35] Rijijohn [36] ), metals (Cerqueira and Fernandes [37] and Martinez et al.[38] ) and organic contaminants (Rosety-Rodriguez et al.[39] and Fanta et al.[40] ). The secondary lamellae were almost lost and damage of gill arch was very high, leading to the formation of vacuoles [Figure 3]e. The gill showed degeneration and necrosis of arch leading to the formation of vacuum space and the primary, secondary lamellae were damaged to great extent. The primary lamellae showed excessive proliferation [Figure 3]f. Cirrhinus mrigala being the bottom dweller was in continuous contact with deterioted pond bottom and gills were the primary organs of inflammation of various toxicants, irritants and other hazardous wastes leading to such proliferative changes. These results corroborated with works of Dykova and Lom, [41] McCraren et al.[42] in Catla catla. The present observations were supported by Hassan, [43] who reported the epithelial lining cells of the secondary lamellae with proliferative changes, including, hyperplasia and hypertrophy. The histopathological changes in events of massive infections by ectoprotozoans Trichodinella epizootica in carp (Lom) [44] and Tripartiella cichlidarum in cichlids (Paperna) [12] cause some erosion of the gill. The present observations were also supported by Paperna and Van, [45] who reported that the parasitism with Chilodonella hexasticha produced severe gill damage in the form of epithelial hyperplasia. Langdon et al.[46] reported that heavy C. hexasticha infestation caused mass mortality among farmed and wild fish.
Brain
The brain of the Catla catla showed presence of protozoan parasites in the tissues leading to necrosis. Black pigmentation, vacuolization of myelin sheath of nerve fibers were some of the common degenerative changes observed in brain tissue [Figure 4]a. At high magnification the brain of the Catla catla showed the presence of distinct protozoan cyst, vacuolization, degeneration and necrosis [Figure 4]b. | Figure 4: (a) The brain of the Catla catla showing presence of protozoan parasites in brain tissue (red arrow), black pigmentation observed (yellow arrow), vacuolization (black arrow) were observed in the brain tissue (H&E, 40x) (b) High magnification the brain of the Catla catla showing the presence of distinct protozoan cyst (red arrow), vacuolization (black arrow) also observed (H&E, 100x) (c) The brain of the Labeo rohita showing damage of nerve fibers with prominent vacuolization (green arrow), rush of blood cells indicating onset of the primary inflammatory response (yellow arrow) (H&E, 40x) (d) The brain of the Labeo rohita showing complete degeneration and necrosis of nerve fibers with the clear vacuolization (green arrow), presence of protozoan cyst was the characteristic of this slide (red arrow) (H&E, 40x) (e) The brain of the Cirrhinus mrigala showing complete degeneration and necrosis of nerve fibers with clear cut vacuolization (red arrow), presence of protozoan parasite (light blue arrow) were observed (H&E, 40x) (f) The brain of the Cirrhinus mrigala showing presence of protozoan cyst (blue arrow), haemocytic infiltration (yellow arrow) as a mark of inflammatory response was noticed (H&E, 40x)
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The brain of the Labeo rohita showed damage of nerve fibres with prominent vacuolization, rush of blood cells indicating the onset of the primary inflammatory response [Figure 4]c. The brain showed complete degeneration, necrosis of nerve fibres' with the clear vacuolization and presence of protozoan cyst [Figure 4]d.
The brain of Cirrhinus mrigala showed complete degeneration and necrosis of nerve fibres with clear vacuolization. Vacuolization in brain tissue might be the result of glycolysis leading to microsomal and mitochondrial dysfunctions. Severe necrosis of neural fibres evident in this work was also supported by the studies of Loganathan et al.[47] Presence of protozoan parasites was another characteristic feature and the brain cells damaged to great extent [Figure 4]e. The brain tissue showed presence of protozoan cyst with rush of blood cells as a mark of inflamatory response and degeneration of nerve cells were quite evident [Figure 4]f. The protozoan parasites penetrate the skin and migrate through subcutaneous tissue and muscle finally enter to the blood vessels to make their way to the brain region. This was similar with the findings of the migration of Diplostomum spathaceum by Ferguson [48] and Posthodiplostomum minimum by Hoffman. [49] A smaller number probably enter the brain directly through the soft parts of the cranium or by route of the cranial nerves.{Figure 4}
| Acknowledgement | | |
Authors are thankful to the Indian Council of Agricultural Research (ICAR), New Delhi for financial support under the Niche Area of Excellence.
| References | | |
| 1. | Lom G. Trichodinidae and other ciliates (Phylum: Ciliphora). In: Woo PTK, editor. Fish Diseases Disorders: Protozoan and Metazoan Infections. Wallingford, CAP International. 1995. p.229-262.  |
| 2. | Younis AA, Gharib AE, Tantawy EA. Studies on some prevailing parasites affecting Oreochromis niloticus fingerlings with a trial of treatment. Egypt J Aquat Biol and Fish 2009;13:135-48. |
| 3. | Osman AF. Studies on Parasitic Gill Affections in Some Cultured Fresh Water Fishes. Suez Canal University; 2001. |
| 4. | Lom J, Dykova I. Protozoan Parasites of Fishes. Amsterdam: Elsevier Science Publishers; 1992. p. 242. |
| 5. | Uzbilek MK, Yilidiz HY. A report on spontaneous diseases in the culture of grass carp Turkey. Turk Veterinerlik Ve Hayvancilik Dergisi 2002;26:407-10. |
| 6. | Durborow RM. Protozoan Parasites. Available from: Error! Hyperlink reference not valid. [Last accessed on 2003]. |
| 7. | Pearse L. A note on a marine trichodinid ciliate parasitic on the skin of captive flatfish. Aquaculture 1972;1:261-6. |
| 8. | Reed P, Ruth FF, Ruth EK. Monogenean Parasites of Fish. Available from: http://www.edis.ifas.ufl.edu. [Last accessed on 2003 Sept]. |
| 9. | Soulsby EJ. Helminths, arthropods and protozoa of domesticated animals. 7th ed. London: ELBS (Educational Low-Priced Book Scheme); 1982. p.809. |
| 10. | Moeller RB. Diseases of Fish. California Animal Health and Food Safety Laboratory System. California: University of California; 2001. |
| 11. | Bowser PR. Diseases of Fish. Ithaca, New York; 1999. p.14853-6401. |
| 12. | Paperna I. Diseases caused by parasites in the aquaculture of warm water fish. Ann Rev Fish Dis 1991;1:155-94. |
| 13. | Lakra WS, Abidi R, Singh AK, Sood N, Rathore G, Swaminathan TR. Fish Introductions and Quarantine Indian Perspective. Lucknow: National Bureau of Fish Genetic Resources; India: 2006. p. 198. |
| 14. | Mohan CV, Bhatta R. Social and economic impacts of aquatic animal health problems on aquaculture in India. In: Arthur JR, Phillips MJ, Subasinghe RP, Reantaso MB, MacRae IH, editors. Primary Aquatic Animal Health Care in Rural, Small-scale, Aquaculture Development. Rome: Food and Agriculture Organization of the United Nations; 2002. p. 63-75. |
| 15. | Vineetha P, Abraham TJ. Risk factors, management issues and economic impacts of diseases on carpaqua culture in Andhra Pradesh. J Rural Dev (Hyderabad) 2009;28:49-63. |
| 16. | Sil SK, Abraham TJ, Nagesh TS. Risk factors, management issues and economic impacts of diseases on carp aquaculture in West Bengal, India. Indian J Fish 2013. (In press). |
| 17. | Roberts RJ. The parasitology of teleost. In: Roberts RJ, editor. Fish Pathology. London: W. B. Saunders; 2001. P. 254-296. |
| 18. | Yu Y, Wu B. Histological studies on the twist diseases of Hypophthalmicthys molitrix. J Zhejiang Coll Fish 1992;11:95-97. |
| 19. | Yokote M. Digestive system. In: Hibiya T, editor. An Atlas of Fish Histology: Normal and Pathological Features. Tokyo: Kodansha Ltd.; 1982. p. 74-93. |
| 20. | Mishra BK, Kumar D, Dey RK, Suresh K. Observation on renal myxosporidiasis in Indian major carps. Abst Proc Symp on Diseases of Finfish and Shelfish. Mangalore, Karnataka: College of fisheries; 1982. p. 1-3. |
| 21. | Gupta S, Dalela RC. Kidney damage in Notopterus notopterus (Pallas) following exposure to phenolic compounds. J Environ Biol 1987;82:167-172. |
| 22. | Csepai E. Histological detectable dystrophies in the carps kidney exposed to chronic effect of some pesticides. Magy Allatorv Lapja 1978;33:55-58. |
| 23. | Konar SK. Hazards of Water Pollution by Pesticides: Symposium on Environmental Pollution and Toxicology. Haryana: Haryana Agricultural University and Indian National Science Academy; 1977. p. 83-94. |
| 24. | Bakthavathsalam R, Ramalingam R, Ramaswamy A. Histopathology of liver, kidney and intestine of the fish Anabas testudineus exposed to Furadan. Environ Ecol 1984;2:243-247. |
| 25. | Dubale M, Saha P. Histopathology of the kidney of the fish Channa punctatus exposed to cadmium. J Anim Morphol Physiol 1981;291:166-171. |
| 26. | Rashatwar SS, Ilyas IC. Effect of phosphomidon in a freshwater teleost fish Nemachelius denisonii Day - histopathological and biochemical studies. J Environ Biol 1984;5:1-18. |
| 27. | Perisetti B. Effect of Nuvan on Labeo Rohita Under Laboratory Condition. Kolkata: West Bengal University of Animal and Fishery Sciences; 2011. p. 103. |
| 28. | Dey RK, Kumar D, Mishra K. Tissue level reaction in the Indian major carp, Catla catla (Ham.) due to Myxoholus sp. Infection. Asian Fish Soc 1988;1:117-122. |
| 29. | Ghosh AK, Dutta NC, Laha GC. Observations on dactylogyrid trematodes of Catla catla from Hooghly, West Bengal. J Inland Fish Soc India 1987;192:53-60. |
| 30. | Sanaullah M, Ahmed AT. Gill myxoboliasis of major carps in Bangladesh. J Fish Dis 1980;3:349-354. |
| 31. | Ramudu RK, Dash G. Toxins released by various parasites/pathogens and their effects: Alternative remedy for good health: A Review. SEBA Newsletter 2013;5:4-8. |
| 32. | Lowe JI. Chronic exposure to Leiostomus xanthurus L. to sublethal concentration of toxophene in sea water. Trans Amer Fish Soc 1964;93:396-399. |
| 33. | Eller LL. Histological lesions in cutthroat trout ( Salmo clarki) exposed chronically to the insecticide endrin. Am J Pathol 1971;64:321-336. [ PUBMED] |
| 34. | Jauch D. Gill lesions in Cichlid fishes after intoxication with the insecticides Fenthion. Experientia 1979;35:371-372. [ PUBMED] |
| 35. | Nowak B. Histological changes in gills induced by residue of endosulfan. Aqua Toxicol 1992;23:65-83. |
| 36. | John KR, Jayabalan N. Sublethal effects of endosulfan on the histology and protein pattern of Cyprinus carpio gill. J Appl Ichthyol 1993;9:49-56. |
| 37. | Cerqueira CC, Fernandes MN. Gill tissue recovery after cooper exposure and blood parameter responses in the tropical fish Prochilodus scrofa. Ecotoxicol Environ Saf 2002;52:83-91. |
| 38. | Martinez CB, Nagae MY, Zaia CT, Zaia DA. Acute morphological and physiological effects of lead in the neotropical fish Prochilodus lineatus. Braz J Biol 2004;64:797-807. |
| 39. | Rosety-Rodríguez M, Ordoñez FJ, Rosety M, Rosety JM, Rosety I, Ribelles A, et al. Morpho-histochemical changes in the gills of turbot, Scophthalmus maximus L., induced by sodium dodecyl sulfate. Ecotoxicol Environ Saf 2002;51:223-228. |
| 40. | Fanta E, Rios FS, Romão S, Vianna ACC, Freiberger S. Histopathology of the fish Corydoras paleatus contaminated with sublethal levels of organophosphorus in water and food. Ecotoxicol Environ Saf 2003;54:119-130. |
| 41. | Dykova I, Lom J. Histopathological changes in fish gills infected with Myxosporidian parasites of the genus Henneguya. J Fish Biol 1978;12:197-202. |
| 42. | McCraren JP, Landolt ML, Hoffman GL, Meyer FP. Variation in response of channel catfish to Henneguya sp. Infections (Protozoa: Myxosporidea). J Wildl Dis 1975;11:3-7. [ PUBMED] |
| 43. | Hassan MA. Trichodiniasis in Farmed Freshwater Tilapia in Eastern Saudi Arabia. J KAU: Mar Sci 1999;10:157-168. |
| 44. | Lom J. The adhesive disc of Trichodinella epizootica. Ultrastructure and injury to the host tissue. Folia Parasitol (Prague) 1973;20:193-202. |
| 45. | Paperna I, Van As JG. Epizootiology and pathology of Chilodonella hexasticha (Kiernik, 1909) (Protozoa, Ciliata) infections in cultured cichlid fishes. J Fish Biol 1983;23:441-450. |
| 46. | Langdon JS, Gudkovs N, Humphrey JD, Saxon EC. Deaths in Australian freshwater fishes associated with Chilodonella hexasticha infection. Aust Vet J 1985;62:409-413. [ PUBMED] |
| 47. | Loganathan K, Velmurugan B, Hongray Howrelia J, Selvanayagam M, Patnaik BB. Zinc induced histological changes in brain and liver of Labeo rohita (Ham.). J Environ Biol 2006;27:107-110. |
| 48. | Ferguson MS. Migration and localization of an animal parasite within the host. J Exp Zool 1943;93:375-401. |
| 49. | Hoffman GL. Experimental studies on the cercaria and metacercaria of a strigeoid trematode, Posthodiplostomum minimum. Exp Parasitol 1958;7:23-50. [ PUBMED] |
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
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