Abstract: Ultrastructure of spermatozoa was investigate in both fresh and frozen seminal fluid by ultra-low temperature freezing collected from male black rockfish Sebastesschlegelii weighting 500-750 g by histological method, scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the spermatozoa had elongated nuclei and the concentrated chromatin during spermatogenesis. The mature spermatozoa had leaf-shaped heads, without acrosome, and mitochondria were transferred toward the base of tail for the energy supply during the tail movement. Flagellum was composed of mitochondria, and axoneme shaped in with lateral fin. Frozen spermatozoa showed significant variation in morphology, most of which showed tail breakage, some lost mitochondria, and damaged mitochondrial cristae and cell membrane, although a few spermatozoa were normal. These the findings indicated that the head shape and the number of mitochondria of spermatozoa in ovoviviparous black rockfish are significantly different from those in oviparous fish and it is speculated that most of spermatozoa have weakened or no ability of fertilization after deep-freezing.
2020, Vol. 35 
