Transmission electron microscopic observations on spermatozoa in seven species of puffers genus Takifugu (Tetraodontidae, Tetraodontiformes)

The cryopreserved spermatozoa of seven species of puffer, Takifugu niphobles, T. pardalis, T. poecilonotus, T. porphyreus, T. radiatus, T. rubripes, and T. xanthopterus were observed with a transmission electron microscope. The spermatozoa of these species had a round-shaped head, a midpiece which contained mitochondria, and a tail. The nucleus of the spermatozoa of the seven species are unusually elongate, and the chromatin of the nucleus is an electron dense structure. In the midpiece, 7- 9 independent mitochondria encircle the flagellum of the spermatozoa. The axoneme has two lateral fins relative to which the plane of the two central singlets is slightly tilted. Internal morphology of the spermatozoa of the seven Takifugu species closely resemble one another in their head structure, mid-piece structure, and axoneme structure. It is concluded that the spermatozoa of the seven species can not be readily identified from their morphology.