Cellular evidence for nano-scale exosome secretion and interactions with spermatozoa in the epididymis of the Chinese soft-shelled turtle,Pelodiscus sinensis

// Hong Chen 1 , Ping Yang 1 , Xiaoya Chu 1 , Yufei Huang 1 , Tengfei Liu 1 , Qian Zhang 1 , Quanfu Li 1 , Lisi Hu 1 , Yasir Waqas 1 , Nisar Ahmed 1 and Qiusheng Chen 1 1 Laboratory of Animal Cell Biology and Embryology, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu Province, China Correspondence to: Qiusheng Chen, email: // Keywords : Chinese soft-shelled turtle; nano-scale exosomes; spermatozoa; epididymis; interaction; Pathology Section Received : December 02, 2015 Accepted : February 24, 2016 Published : March 15, 2016 Abstract The epididymis is the location of sperm maturation and sperm storage. Recent studies have shown that nano-scale exosomes play a vital role during these complicated processes. Our aim was to analyze the secretory properties of epididymal exosomes and their ultrastructural interaction with maturing spermatozoa in the Chinese soft-shelled turtle. The exosome marker CD63 was primarily localized to the apices of principal cells throughout the epididymal epithelium. Identification of nano-scale exosomes and their secretory processes were further investigated via transmission electron microscopy. The epithelium secreted epididymal exosomes (50~300 nm in diameter) through apocrine secretion and the multivesicular body (MVB) pathway. Spermatozoa absorbed epididymal exosomes through endocytosis or membrane fusion pathways. This study shows, for the first time, that nano-scale exosomes use two secretion and two absorption pathways in the reptile, which may be contribute to long-term sperm storage.