| Summary: | 碩士 === 國立臺灣大學 === 臨床動物醫學研究所 === 107 === Background: Advances in medical diagnosis and management is warranted for the conservation of endangered chelonian species. Disagreement and deficiency exist among past studies on sea turtles’ leukocytes differentiation, and no published morphologic or ultrastructural study on Mauremys mutica and Cuora flavomarginata was available. Widely used as an important indication of systemic inflammation and prognosis in many species, heterophil toxic change is, however, poorly understood in sea turtles.
Objectives: This study aims to identify and characterize the circulating leukocytes in 5 endangered turtle species in Taiwan, compare the efficacy of accessible staining methods, and provide better understanding of the clinical applications and limitations of toxic change examination in sea turtles.
Methods: Blood samples were collected from 30 rescued sea turtles (21 Chelonia mydas, 6 Lepidochelys olivacea and 3 Eretmochelys imbricata), 8 captive Mauremys mutica and 7 captive Cuora flavomarginata from January 2017 to September 2018. Morphologic and ultrastructural examination were performed using standard methods.
Results: 5 types of leukocytes were identified in each species: heterophils, eosinophils, basophils, lymphocytes and monocytes. Morphologic features were generally comparable to similar species. Two types of eosinophils (large and small) were seen in sea turtles. Basophils of sea turtles were similar to those of other reptile and avian species. Ultrastructurally, heterophil granules were unevenly distributed. No crystalloid granulations were observed in eosinophils of sea turtles. The granulocytes ultrastructure of Mauremys mutica and Cuora flavomarginata were similar to those of Trachemys scripta scripta and Hieremys annandalii, but the polygonal crystalloid structures seen in the basophil granules of Cuora flavomarginata have not been reported in other species of freshwater turtles. Toxic heterophils in sea turtles were characterized with uneven staining of cytoplasmic granules, increased cytoplasmic basophilia, degranulation, and the presence of prominent basophilic cytoplasmic granules. Ultrastructurally, toxic heterophils had smooth cellular membrane, reduced cytoplasmic granules that were smaller or more variable in size, and cytoplasm containing much greater amount of membranous organelles and clusters of dark polyribosomes. There was no significant difference among Wright Giemsa stain, Diff-Quik stain and Liu’s stain on the efficacy of leukocyte differentiation, however Wright-Giemsa’s stain and Liu’s stain were significantly superior than Diff-Quik stain for assessing toxic change. Microscopic examination of toxic change is comparable to TEM examination, however the correlation of the presence toxic change with both clinical inflammatory state and the treatment outcome is both weak and insignificant in sea turtles.
Conclusions: The differentiation and characteristics of circulating leukocytes of 5 endangered chelonian species was clarified and described in details, each complemented with high quality micrographs. Toxic change morphology in sea turtles and toxic change ultrastructure in reptile species were described for the first time in this study. This study provided fundamental hematologic information for endangered turtle species and insights to further investigations on clinical pathology and immunity of these species.
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