Histopathology of Selected Parasitic Salmonid Diseases: A Color Atlas

Science Center Objects

A collection of 77 photomicrographs compiled by the late William T. Yasutake, USGS Western Fisheries Research Center, Scientist Emeritus. Individual plates may be downloaded below.

PLATE 1

Photomicrographs of Figure 1: Ichthyobodo necator (Costia) are attached to the gill surface (arrow) of a yearling sockeye salmon, Oncorhynchus nerka. Figure 2: I. necator (arrow) are attached to several loose skin epidermal cells of a fingerling rainbow trout, O. mykiss. Figure 3: Thecamoeba hoffmani (arrow), an amoeba, in wet mount made from gill scraping of a fingerling Chinook salmon, O. tchawytscha.

PLATE 2

Photomicrographs of Figure 4: T. hoffmani in gill section of a fingerling Chinook salmon. Figure 5: T. hoffmani (arrow) higher magnification. Figure 6: Icthyophthirius multifiliis in the gill of a fingerling rainbow trout.

PLATE 3

Photomicrographs of Figure 7: I. multifilitiis (arrow) in the epidermis of a spawning coho salmon O. kisutch. Figure 8: Trichodina sp. from a juvenile coho salmon gill scraping. Figure 9: Trichodina sp. (arrows) between the lamellae of a juvenile coho salmon.

PLATE 4

Photomicrographs of Figure 10: Cross section of Trichodina sp. between gill lamellae of a fingerling coho salmon, O. kisutch. Figure 11: Trichophrya sp., a suctoran ciliate. Figure 12: Trichophrya sp. (arrows) on the gill section of a fingerling sockeye salmon.

PLATE 5

Photomicrographs of Figure 13: Trypanoplasma (Cryptobia) salmositica, a hemoflagellate, in peripheral blood smear of a young rainbow trout. Figure 14: T. salmositica in the gill blood vessels of an infected steelhead, O. mykiss (arrows). Figure 15: T. salmositica with prominent kinetoplasts (arrows) in the central vein of the liver of a fingerling Chinook salmon.

PLATE 6

Photomicrographs of Figure 16: Spironucleus (Hexamita) salmonis (arrow). Figure 17: Ceratomyxa shasta. Figure 18: C. shasta in wet mount with pansporoblasts.

PLATE 7

Photomicrographs of Figure 19: C. shasta trophozoites in the lamina propria of a spawning coho salmon pyloric cecum. Figure 20: C. shasta trophozoites. Figure 21: C. shasta trophozoites and spores in the lamina propria of spawning coho salmon pyloric cecum

PLATE 8

Photomicrographs of Figure 22: C. shasta trophozoites and spores. Figure 23: Myxobolus (Myxosoma) cerebralis infection in yearling cutthroat trout, O. clarki, showing scoliosis and lordosis. Figure 24: M. cerebralis spores (arrow) in wet mount made from infected fingerling steelhead trout, O. mykiss.

PLATE 9

Photomicrographs of Figure 25: M. cerebralis infected fingerling rainbow trout with various stages of trophozoites and histo- pathological changes. Figure 26: M. cerebralis trophozoites in fingerling rainbow trout. Figure 27: M. cerebralis trophozoites and spores in the gill arch of fingerling rainbow trout.

PLATE 10

Photomicrographs of Figure 28: M. cerebralis spores in yearling rainbow trout. Figure 29: Myxobolus squamalis spores in the scale of a fingerling rainbow trout (arrow). Figure 30: M. squamalis spores in the scale of a fingerling rainbow trout.

PLATE 11

Photomicrographs of Figure 31: Myxobolus sp. spore in wet mount showing iodinophilous vacuole in the sporoplasm (arrow). Figure 32: Myxobolus sp. spores (arrows) in the dorsal striated muscle of a yearling coho salmon. Figure 33: Myxobolus sp. spores (arrow).

PLATE 12

Photomicrographs of Figure 34: Myxobolus kisutchi spores (arrows) in the spinal cord of a fingerling coho salmon. Figure 35: M. kisutchi spores in the spinal cord, just posterior to the medulla oblongata of the fingerling coho salmon. Figure 36: Parvicapsula sp., myxosporean spores (arrows) in wet mount of pen-reared yearling coho salmon kidney.

PLATE 13

Photomicrographs of Figure 37: Parvicapsula sp. trophozoites and spores in fingerling coho salmon kidney tissue section. Figure 38: Parvicapsula sp. trophozoites and spores in kidney tubules of a fingerling coho salmon. Figure 39: Parvicapsula sp. trophozoites and spores in kidney tubule of a fingerling coho salmon.

PLATE 14

Photomicrographs of Figure 40: Proliferative kidney disease (PKD). Figure 41: PKD organism (arrow) in kidney imprint from a 6-month-old rainbow trout. Figure 42: PKD infected 7-month-old rainbow trout kidney showing proliferative tissue response (arrow).

PLATE 15

Photomicrographs of Figure 43: PKD infected 5-month-old rainbow trout kidney showing several T. bryosalmonae. Figure 44: PKD organism, T. bryosalmonae (arrow), in the gill lamella of an infected rainbow trout. Figure 45: T. bryosalmonae (black arrow) in the dorsal muscle of an infected rainbow trout.

PLATE 16

Photomicrographs of Figure 46: Chloromyxum majori spores (arrow) in wet mount made from an adult rainbow trout kidney. Figure 47: C. majori trophozoites and spores in kidney glomeruli of a 6-month-old Chinook salmon. Figure 48: C. majori trophozoites and spores.

PLATE 17

Photomicrographs of Figure 49: Myxidium sp. infection in the liver of a 4-year-old rainbow trout. Figure 50: Myxidium minteri trophozoites and spores in the lumen of a fingerling steelhead trout kidney tubules. Figure 51: Myxidium sp. cyst in a 2-year-old rainbow trout liver.

PLATE 18

Photomicrographs of Figure 52: Henneguya zschokkei. Figure 53: H. zschokkei spores in a sectioned cyst from a yearling rainbow trout body muscle. Figure 54: Henneguya sp. spores from a cyst in muscle of a rainbow trout.

PLATE 19

Photomicrographs of Figure 55: Kudoa thyrsites (arrow) in body muscle of a yearling Atlantic salmon. Figure 56: K. thyrsites spores in the striated body musculature of a yearling Atlantic salmon. Figure 57: Nucleospora (Enterocytozoon) salmonis infected fingerling steelhead kidney imprint.

PLATE 20

Photomicrographs of Figure 58: N. salmonis. Figure 59: N. salmonis. Figure 60: N. salmonis infected fingerling steelhead with perivascular cuffing of affected hepatic cells (arrow).

PLATE 21

Photomicrographs of Figure 61: N. salmonis. Figure 62: N. salmonis. Figure 63: Loma sp. a microsporidian, in a luamellar cyst of a 2-year-old steelhead trout.

PLATE 22

Photomicrographs of Figure 64: Pleistophora sp. a microsporidian, in a lamellar cyst of a 2-year-old steelhead trout. Figure 65: Sanguinicola sp. Figure 66: Sanguinicola sp.

PLATE 23

Photomicrographs of Figure 67: Sanguinicola sp. cyst (arrow) in the capillary of a gill lamella of a cutthroat trout, Salmo clarki. Figure 68: Sanguinicola sp. Figure 69: Sanguinicola sp.

PLATE 24

Photomicrographs of Figure 70: Nanophyetus salmincola (commonly known as the salmon poisoning fluke) metacercariae (arrows) in the kidney of an adult coho salmon. Figure 71: N. salmincola metacercaria in the heart ventricle of a spawning coho salmon. Figure 72: N. salmincola metacercaria (a) in thyroid tissue (b) area of a yearling coho salmon.

PLATE 25

Photomicrographs of Figure 73: Diplostomum sp. metacercariae (arrows) in the anterior chamber of an adult rainbow trout eye. Figure 74: Diplostomum sp. metacercariae (arrows) in the lens of a yearling rainbow trout eye. Figure 75: Diplostomum sp. metacercariae (arrows) between the choroid (a) and the retina (b) and in the vitreous chamber (c) of a yearling rainbow trout eye.

PLATE 26

Photomicrographs of Figure 76: Dermocystidium salmonis, a mesomycetozoon. Figure 77: Higher magnification of Fig. 76. D. salmonis cyst in the distal end of the gill filament.

The entire set of micrographs may be downloaded here

Acknowledgements

Thanks to the following individuals for their contribution of photomicrographs for this project: John Moldin, California State Fish and Game; the late Dr. Clearance Becker, Battelle Northwest; the late James Wood, Washington State Fish and Game; the late Harold Wolf, California Fish and Game; Charlie Smith, U. S. Fish and Wildlife Service; Robert Troth, California Fish and Game; Beth MacConnell, U. S. Fish and Wildlife Service; John Morrison, U. S. Fish and Wildlife Service; Bruce M. Bortz, Washington Cooperative Fishery Research Unit; Dr. Robert Olsen, Hatfield Marine and Science Museum, Newport, OR.

A special thanks to Drs. James Winton, Diane Elliott and Gary Wedemeyer, U.S. Geological Survey, Western Fisheries Research Center, Seattle, Washington, for reviewing the final draft of the manuscript. I am also indebted to the late Dr. A. C. Fox, former Director and Dr. J. Rolland, the present Director of the Western Fisheries Research Center.