Ultrastructural characteristics of blood cells in the Yellow-Bellied Slider Turtle (Trachemys scripta scripta).

BACKGROUND The classification of blood cells from the Yellow-Bellied Slider Turtle (Trachemys scripta scripta) is relevant due to their increasing importance as pets and as object of study in clinical settings and research projects. However, no previous ultrastructural characterization of blood cells from turtles of the genus Trachemys has been reported. OBJECTIVES The objective of this study was to provide an ultrastructural characterization of blood cells of the Yellow-Bellied Slider Turtle. METHODS Blood samples from 10 healthy adult turtles (5 males and 5 females) were obtained and processed for transmission electron microscopy using standard methods. RESULTS Some erythrocytes had intracytoplasmic inclusions compatible with hemoglobin precipitates; mitochondria and ribosomes in the cytoplasm of erythrocytes were also observed. Five types of white blood cells were ultrastructurally identified: heterophils, eosinophils, basophils, lymphocytes, and monocytes. Heterophils were similar to those described from Sea Turtles, with only one morphologic variation of this cell. Eosinophils were homogeneous in size and had intracytoplasmic granules without crystalline structures. Basophils were ultrastructurally described for the first time for a turtle and had heterogeneous intracytoplasmic granules. Lymphocytes and monocytes were similar to those described from other chelonians. Some thrombocytes had an irregularly lobulated nucleus and intracytoplasmic canalicular structures. CONCLUSION This study provides the first ultrastructural classification of blood cells in Trachemys scripta scripta, as a baseline for further hematologic studies in this species.