Abstract: This study was conducted to investigate Brachymystax lenok tsinlingensis spermatozoa cell morphologyand ultrastructure through scanning and transmission electron microscopy. Findings revealed that thespermatozoa can be differentiated into three major parts: a spherical head without an acrosome, a shortmid-piece, and a long, cylindrical flagellum. The mean length of the spermatozoa was 36.11 ± 2.84 m,with a spherical head length of 2.78 ± 0.31 m. The mean anterior and posterior head widths were 2.20 ± 0.42 m and 2.55 ± 0.53 m, respectively. The nuclear fossa was positioned at the base of thenucleus that contained the anterior portion of flagellum and a centriolar complex (proximal and distalcentrioles). The short mid-piece was located laterally to the nucleus and possessed just one sphericalmitochondrion with a mean diameter of 0.65 ± 0.14 m. The spermatozoa flagellum was long and cylin-drical, and could be separated into two parts: a long main-piece and a short end-piece. The main piece of the flagellum had short irregular side-fins. The axoneme composed the typical ‘9 + 2’ microtubular dou-blet structure and was enclosed by the cell membran e. This study confirmed that B. lenok tsinlingensis spermatozoa can be categorized as teleostean “Type I” spermatozoa; ‘primitive’ or ‘ect-aquasperm type’spermatozoa. To the best of the authers knowledge, this was the first study conducted on the morphologyand ultrastructure of B. lenok tsinlingensis spermatozoa.

Wei Guo, Jian Shao, Ping Lic, Jinming Wu, Qiwei Wei. Morphology and ultrastructure of Brachymystax lenok tsinlingensisspermatozoa by scanning and transmission electron microscopy. Tissue and Cell, 2016.