Characterization of Extracellular Vesicles from Cilia and Epithelial Cells of Ductuli Efferentes in a Turtle (Pelodiscus sinensis)

摘要

Ductuli efferent is a conduit passage of spermatozoa from rete testis to the epididymis. After spermiation, various extracellular vesicles are released by epithelial cells to assist and transfer micro-molecules for spermatozoa maturation. To date, there is a lack of data in ductuli efferent. In this study, we investigate the distribution, classification, and source of multivesicular bodies (MVBs) and their extracellular vesicles (EVs) in the epithelia of efferent ducts in a turtle by using light and transmission electron microscopy. Immunohistochemistry of CD63 (Cluster of differentiation 63) and ultrastructure demonstrates that ciliated and non-ciliated cells of ductuli efferent possess well developed exocytic systems. Ciliated cells and non-ciliated cells secrete extracellular vesicles via ciliary blebs and apical blebs, respectively. Results also showed numerous extracellular vesicles between these cells and indicate basolateral secretion. Moreover, these extracellular vesicles are associated with spermatozoa in the lumens of ductuli efferentes. Collectively, the present study provides cytological evidence that the ductuli efferentes (DE) epithelium secretes EVs to the lumen by (1) apical blebs, (2) ciliary blebs, and (3) from the basolateral region. Characterization and cellular distribution of these extracellular vesicles in the ductuli efferent of turtles may provide a study model to further investigate the transferring of micro-molecules via extracellular vesicles to the spermatozoa.