൲asites. Note that not all types of parasites are illustrated. · 2010. 3. 5. · Avian...
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Avian Histopathology Learning Module 1-Learning Component 5 Features (“Things”) Parasites
Transcript of ൲asites. Note that not all types of parasites are illustrated. · 2010. 3. 5. · Avian...
Avian HistopathologyLearning Module 1-Learning Component 5
Features (“Things”)Parasites
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This is learning component 5 in learning module 1. In this component, we will show some features that are characteristic of parasites. Note that not all types of parasites are illustrated.
Protozoa
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We will begin by showing an example of protozoa. Coccidia are the most important protozoa causing economic loss in commercial poultry.
Example - Coccidiosis
• Chicken – Duodenum• Presence of Several Life cycle States of E.
acervulina in Enterocytes
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This example will illustrate typical features characteristic of Eimeria acervulina in the duodenum of chickens.
A B
C D
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A is a low power view of the mucosa of the duodenum. Even at this magnification, numerous trophozoites of E. acervulina can be seen just beneath the surface and above the nucleus of enterocytes . B is a higher magnification of A showing numerous trophozoites just beneath the surface of enterocytes. C is a higher magnification of B. D shows several life-cycle stages of E. acervulina including trophozoites and zygotes.
Example - Histomoniasis
• Expansion of Lamina Propria in Cecum by Large Numbers of Protozoal Parasites (Histomonads) with Accompanying Lymphohistiocytic Inflammation
• Replacement of Hepatocytes by Large Numbers of Histomonads
• Histomonads in Giant Cell in Liver
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This case of histomoniasis (Black Head) shows expansion of the lamina propria of the cecum by a lymphohistiocytic inflammation and by intralesional protozoa typical of Histomonas melegaridis. Also shown in this example are histomonads in a liver with lesions of massive necrosis. Look for the presence of protozoa within the cytoplasm of giant cells.
A B
C D
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A shows the mucosa of the cecum with an expanded lamina propria containing lymphocytes and protozoa. B is a higher magnification of A sowing protozoa typical of Histomonas melegaridis (arrows). C is a low power view of liver showing an area of necrosis with intralesional protozoa. D is a higher magnification of C and shows the histomonads; some are within the cytoplasm of a giant cell.
Example - Nematode
• Heterakis in Cecum• Tube Within a Tube• Lateral Alae• Expansion of Lamina Propria with
Lymphohistiocytic Cells
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This example will show the features of a nematode – Heterakis – having characteristic features of an internal alimentary tract (tube within a tube structure) and lateral alae. The lamina propria of the cecum is expanded by lymphohistiocytic cells.
A B
C D
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A is a low power view of cecum showing cross sections of a nematode parasite (most likely Heterakis) in the lumen and mucosa. B shows the central alimentary tract and projections from the cuticle termed lateral alae. C and D are higher magnification of this nematode.
Tapeworms
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Features of tapeworms are shown in the next two images. You should note that they are segmented, do not have a central alimentary tract, and have calcified material termed calcareous corpuscles in the lateral body wall.
A B
C D
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Images A-D show tapeworms in the small intestine of a backyard chicken. Note the characteristic segments and the numerous round dark-staining mineral deposits termed calcareous corpsucles.
A B
C D
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Images A-D show tapeworms in the small intestine of a duck. Note the characteristic segments and the calcareous corpuscles.
Trematodes (Flukes)
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The next set of images show the features of trematodes (flukes). They are flattened and have no segments. Note the characteristic thick-walled eggs.
A B
C D
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Images A-D show flukes in a ureter of a pheasant. Note the flat structure, lack of segments and absence of an internal alimentary tract. Note the large ova with relatively thick walls. Also note the absence of any host response.
Mites
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The next two image show examples of subcutaneous mites and scaly leg mites.
A B
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Image A shows a subcutaneous mite that has calcified. B is a higher magnification. These calcified structures located in subcutaneous tissue are characteristic of subcutaneous mites.
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B C
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Images A-C show the features characteristic of scaly leg mites. Note the large amounts of keratin. This species creates and lives in little “mite houses” composed of excess keratin. Note the spiny projections of the cuticle on the mite in C.
