An Identification Guide for Avian Blood Components

Jordan Briscoe, RIT 2015

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3. Introduction4. Erythrocytes 5. Typical: Reticulocytes 6. Atypical: Poikilocytes 7. Atypical: Stain/Prep Artifacting 8. Atypical: Anemia/Disease9. Heterophils 10. Typical 12. Atypical 13. Atypical: Round Granules 14. Atypical: Stain Artifacting 15. Atypical: Toxic16. Eosinophils 17. Typical & Atypical18. Basophils19. Lymphocytes 20. Typical 21. Atypical 22. Atypical: Reactive23. Monocytes 24. Typical25. Thrombocytes 26. Typical: Clumped 27. Typical: Single28. Parasites 29. Haemoproteus fringillae 30. Microfilaria31. Resources32. The Project

Contents

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The Cell Types

There are a few main types of cell components in avian blood, the erythrocytes (like human erythrocytes- red blood cells), the leukocytes (like human leukocytes-white blood cells), thrombocytes (like human platelets), and occasional parasite.

When studying avian blood, a common method of judging overall health is to count leukocytes by comparing the number of lymphocytes to the number of heterophils in a given area of the sample. Some methods include counting the number of eosinophils as well, and some may make a more inclusive count of all the common leukocytes, which would then include basophils and monocytes. Erythrocytes are very common cells, but are not counted because they are not leukocytes. Thrombocytes function as human platelets do, and while they may give useful information, are also not generally counted. Parasites are abnormal findings in blood samples, and should be studied on an individual basis.

Introduction

A Heterophil A Lymphocyte

Avian erythrocytes are oval shaped cells with nuclei. They are generally larger than mammilian erythrocytes, and can have many variations that are typical in normal blood samples.

Erythrocytes

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Figure 3.

Figure 1.

Reticulocytes are round, immature erythrocytes, These cells have a more basophilic cytoplasm than their mature counterparts and more dispersed chromatin structures in the nuclei. Figure 3 shows a prorubicyte, an early stage of erythrocyte development.

Typical: Reticulocytes

Erythrocytes

Figure 2.

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Figure 5.

Figure 4.

The poikilocyte present in Figure 5 may be irregular as a result of anemia.

Poikilocytes are irregularly shaped erythrocytes that can be present in normal blood samples. Some irregularity may be artifactual from preparation techniques, and some irregularity is simply due to misshapen cells.

Atypical: Poikilocytes

Erythrocytes

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Figure 8.

Figure 6.

The erythrocytes found in Figures 6-8 are atypical due to stain and preparation artifacting. In Figure 6, leftover stain may appear as stained ribosomes, leading to an incorrect identification of a reticulocyte. Figure 7 has a preparation artifact from the glass slide used to make the smear damaging the cells. Figure 8 shows leftover stain, which may be mistaken for a lysed erythrocyte.

Atypical: Stain/Prep Artifacting

Erythrocytes

Figure 7.

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Figure 10.

Figure 9.

The erythrocyte in the top of Figure 10 is a microcyte, which is typical of a subject with iron deficiency anemia. This subject was also stained with a stain that had expired.

In Figure 9, these erythrocytes are polychromatophilic and clumped closely together, which is indicative of an anemic subject. These cells were found in a sample that contained parasites, and the slides were also stained with a stain that had expired. All of these factors contribute to the atypical appearance.

Atypical: Anemia/Disease

Erythrocytes

Heterophils are cell components in avian blood that function similarly to mammilian neutrophils. These cells participate in immune responses, and are phagocytic as well as bacteriocidal.

Heterophils

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Figure 12.

Figure 11.

In Figure 12, the heterophil present is typical, with rod granules. Heterophils typically have lobed nuclei. With a Wright-Giemsa stain, these nuclei appear purple in color.

In Figure 11, the heterophil present is typical, with rod granules. Heterophils are typically round with clear cytoplasm and eosinophilic rod shaped granules.

Typical

Heterophils

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Figure 14.

Figure 13.

In Figure 14, the heterophil to the left is a typical heterophil adjacent to an atypical heterophil. The heterophil to the right is atypical due to a staining artifact.

The heterophil in Figure 13 is typical, however it has unusual granules. The granules are densely packed, and are rod-to-round in shape, which is typical for some species. The cytoplasm is clear, despite some areas looking blueish in tone. This is an artifact from staining, which can also be seen in the erythrocytes beside it.

Typical

Heterophils

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Figure 16.

Figure 15.

These heterophils are atypical because they have round granules and an irregular shape. The distortion of the cells may be due to improper preparation techniques, and the round granules are typical for some species.

The heterophil present in Figure 15 is atypical due to the densely packed granules and slight blue tint to the cytoplasm, which is a staining artifact.

Atypical

Heterophils

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Figure 18.

Figure 17.

The heterophil in Figure 18 may easily be mistaken for an eosinophil due to its blueish appearance in the cytoplasm. This cell is not an eosinophil, however. The blue tint is a result of improper staining, and is not indicative of an eosinophil, due to the number of similar cells in this particular sample.

The heterophil in Figure 17 is atypical due to its round granules. This cell is also slightly distorted, most likely due to improper preparation.

Atypical: Round Granules

Heterophils

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Figure 20.

Figure 19.

In Figure 20, this heterophil appears faded and basophilic. This occurs when a stain has expired, and granules do not stain properly. This cells may be confused easily with a toxic heterophil, which appears very differently with proper staining techniques.

The heterophil in Figure 19 appears to be more basophilic than typical heterophils. It also has less visible eosinophilic granules. This cell is a heterophil, the appearance is due to stain artifacting.

Atypical: Stain Artifacting

Heterophils

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Figure 23.

Figure 21.

Toxic heterophils are an indication of an inflammatory response. The number and severity of the toxicity of the heterophils can be used to infer the severity of an immune response. These toxic heterophils were present in a bird that was infected with blood parasites. Toxic heterophils appear more basophilic overall, with hyper-segmented nuclei, and varying degrees of basophilic granules depending on the level of toxicity.

Atypical: Toxic

Heterophils

Figure 22.

Eosinophils can vary greatly in appearance from species to species. Eosinophils are leukocytes, but their function in avian species is still unclear. It is known that avian eosinophils may not function in the same way as mammilian eosinophils, but it is clear that these cells are active in immune responses.

Eosinophils

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Figure 25.

Figure 24.

The eosinophil present in Figure 25 is atypical due to a stain defect. The granules of the eosinophil are slightly visible, but the cytoplasm stained darker than usual. This could be due to an expired stain being used, or simply an error in the staining process.

The eosinophil found in Figure 24 is a typical eosinophil, with eosinophilic round granules, a dark violet lobed nucleus, and clear-blue cytoplasm. These cells are rarely found in blood samples, as they present themselves in approximately 0-4% of all blood samples.

Typical & Atypical

Eosinophils

Basophils are very uncommon in avian blood smears, only found in about 0-5% of all blood samples. Basophils are primarily involved in immune responses relating to allergic reactions, producing histamines.

Image courtesy of Carmichael Torrance Veterinary Diagnostic Laboratory.

Basophils

http://ctdslab.co.uk/wp-content/uploads/2012/04/Avian-basophil1.jpg

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Lymphocytes in avian species perform the same functions as those in mammilian species, to respond to antigens. These cells produce antibodies as either T-lymphocytes (cell-mediated immunity), or B-lymphocytes (adaptive immunity). These cells are common in avian blood smears.

Lymphocytes

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Figure 27.

Figure 26.

The lymphocyte in Figure 27 is also a typical lymphocyte.

The cell found in Figure 26 is a typical lymphocyte. The cell is round, with a large, non-lobed basophilic nucleus, and a scant rim of blue stained cytoplasm.

Typical

Lymphocytes

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Figure 29.

Figure 28.

In Figure 29, an immunocyte is present.Immunocytes are antigenically stimulated lymphocytes, and appear darker in color and slightly more irregular in shape than typical lymphocytes. Immunocytes are found in diseased subjects or samples from birds that have been recently immunized.

The lymphocyte in Figure 28 is atypical because of its larger size and abnormal shape. The projections of cytoplasm are referred to as “blebs,” and are more commonly found in old blood samples, as the lymphocytes begin to deteriorate.

Atypical

Lymphocytes

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Figure 32.

Figure 30.

Reactive lymphocytes are present due to antigenic stimulation generally from infections. A low number of reactive lymphocytes may be found in a normal blood smear, but a high count is indicative of an immune response. Figures 31 and 32 show reactive lymphocytes as a response to parasitic infection.

Atypical: Reactive

Lymphocytes

Figure 31.

Monocytes are generally the largest leukocytes found in an avian blood smear. These cells are phagocytic, and are also motile using ameboid movements.

Monocytes

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Figure 35.

Figure 33.

Monocytes are cells capable of phagocytosis, and utilize lysosomes to break down and engulf foreign invaders. Monocytes do not have a lobed nucleus, but rather a kidney-shaped nucleus, and a pale blue cytoplasm. Figure 35 shows a monocyte with artifacting due to improper preparation.

Typical

Monocytes

Figure 34.

Thrombocytes are present in avian blood to serve the same purpose as human platelets, to aid in the clotting process (hemostasis). Avian thrombocytes, however, are nucleated, and are not as “sticky” as human platelets, and therefore have less of a tendency to form clots while in arteries where an injury is not present.

Thrombocytes

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Figure 37.

Figure 36.

Figure 37 shows sixteen thrombocytes clumped together in between many erythrocytes. Immature to mature thrombocytes may look very similar to erythrocytes. They are both nucleated, however thrombocyte cytoplasm tends to stain clear, while erythrocyte cytoplasm tends to stain an orange color. These thrombocytes are past maturity and are beginning to deteriorate.

In Figure 36, seven thrombocytes are clumped together, and one single thrombocyte can be found to the left. Thrombocytes tend to clump in blood smears, which can make cell counting difficult.

Typical: Clumped

Thrombocytes

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Figure 39.

Figure 38.

Figure 39 shows a typical thrombocyte that is past maturity, with cytoplasmic projections. These thrombocytes may appear shrunken in comparison to immature thrombocytes, which are less common in peripheral blood smears.

The thrombocyte present in Figure 38 is degenerating. Most thrombocytes found in old blood stains will have a similar appearance to this thrombocyte.

Typical: Single

Thrombocytes

Blood parasites in avian species are very common. While there are many types, two main types of avian parasites will be shown in this guide, Haemoproteus fringillae and microfilaria.

Parasites

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Figure 41.

Figure 40.

Blood parasites such as Haemoproteus fringillae are sensitive to environmental conditions, and may affect avian hosts in one area, but not hosts of the same species in another area.

Haemoproteus fringillae belongs to the largest phylum of blood parasites, Apicomplexa. This parasite infects erythrocytes and reduces the cells’ ability to carry oxygen.

Haemoproteus fringillae

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Figure 43.

Figure 42.

Microfilaria are also sensitive to environmental change. It has been found that increased temperatures associated with global warming positively correlate to the development and spread of this parasite.

Microfilaria are a genus of blood parasite that cannot be identified by morphology. These parasites are nematodes, and remain as extracellular parasites, reducing the health of the host overall by targeting cells in the blood.

Microfilaria

Parasites

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Resourceshttp://ex-epsilon.slu.se:8080/archive/00000869/03/Avian_hematology.pdf

http://people.eku.edu/ritchisong/birdcirculatory.html

https://exoticanimalmed.wordpress.com/2013/09/24/the-various-cells-found-on-avian-blood-smears/

http://avianmedicine.net/content/uploads/2013/03/9.pdf

http://www.owen.fw.msu.edu/White%20Blood%20Cell%20Counts.html

http://www.bioone.org/doi/abs/10.1676/13-124.1

http://ctdslab.co.uk/photos/avian-haematology-photographs/avian-basophil-2/

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This project was completed in May of 2015 as a senior capstone project by Jordan Briscoe, Biomedical Photographic Communications, 2015. The project may not be sold or distributed without permission from the creator. This project is intended for educational purposes only, and was created using the most recent knowledge at the time of creation.

Special thanks is extended to Dr. Susan Smith Pagano (sbssbi@rit.edu) and Ms, Meghan Oberkircher for their assistance and oversight throughout the project.

To view more work or get in contact with Jordan Briscoe, visit www.jbriscoe.com or email jbriscoephoto@gmail.com.

The Project