Table 5. Morphplogical characteristics of blood cells from fish [7, 12, 19].

Cell type	Form of a cell	Cytoplasm	Nucleus	Notes
Thrombocyte	∙ Spiked, spindle, oval or one-nucleus shape [7, 12] ∙ Morphological change by artificial manipulation.(round, oval) [12] ∙ Pseudopodia by stimulation [12] ∙ Many reports of several species [12]	∙ Blue in immature and grayish blue in mature [7] ∙ Granules: young deeply basophilic, intermediate light basophilic [7, 19]	∙ Ribbed arranged chromatin [7] ∙ Indented heterochromatin which transverse the nucleus [19]
Lymphocyte	∙ Round or oval shape [12] ∙ From small to large cell [12] ∙ Produce a pseudopodia by stimulation [12]	∙ Narrow cytoplasm [12] ∙ Blue, graish blue, light blue cytoplasm [12] ∙ Azurophilic granules in cytoplasmic also sometimes seen [17] ∙ Golgi field [12]	∙ Roughly condensed chromatin [12] and dense patched heterochromatin [19] ∙ Round shape [12] ∙ Many cells have cleaved or constriced parts [12] ∙ Occasional nucleus [19]	∙ Resemble to human cell ∙ Plasma cells have been found in the peripheral blood of many fish [19]
Neutrophil	∙ Round or oval shape* [7, 12]	∙ Basophilic color (immature form), light blue, greyish blue and light red cytoplasm [12] ∙ Colorless granules, dark gray, gray granules, light red, bluish red, purplish-red small granules [7, 12] ∙ Two types of granules are formed in immature and mature goldfish [19]	∙ Round,oval,lobe kidney,horseshoe [7, 12] ∙ Several lobes (2–5)* [7, 12]
Basophil	∙ Round shape* [12]	∙ Basophilic cytoplasm [19], light red, dark bluish purple granule* [12] ∙ Light brown cytoplasm (carp,crucian carp) [12] ∙ Pansy large granule (carp,crucian carp) [12]	∙ Densely stained nucleus [12] ∙ Ambiguous chromatin net [12]	∙ Rare appearance [12] ∙ It is easy to release a granule by water and alcohol [12].
Eosinophil	∙ Round or oval shape* [12]	∙ Vermeil-red large granule* [12] ∙ Beige granule (freshwater fish) [12] ∙ Vermeil-red granule (seawater fish) [12]	∙ Sausage-shaped or bilobed eccentric nucleus [19] ∙ Rough condensed and reticulated chromatin* [12]	∙ Easy cytolysis under unsuitable specimen preparation [12]
Monocyte/macrophage	∙ Most large cell in leucocytes * [12] ∙ Oval, irregular or amoeboid * [12] ∙ Pseudopodium [12]	∙ Basophlilic, gray, bluish purple cytoplasm* [12] ∙ Basophilic color at immature form [12] ∙ Scattered purplish red granule around nucleus* [12] ∙ Agranular gray-blue cytoplasm [19] ∙ Vesicle/vacuoles and inclusion [19] ∙ Golgi field does not exist* [12]	∙ Round, kidney type or irregular bilobe* [12] ∙ Rough condensed and linear chromatin* [12]	∙ Resemble to human cell [12]

*: Characteristic of human blood.