Ultrastructural study of spermatozoa of the paddlefish, Polyodon spathula

Abstract

Paddlefish, Polyodon spathula, spermatozoa were examined by transmission electron microscopy. Their structure has the same characteristic architectural features as sturgeon spermatozoa. Paddlefish spermatozoa are of the primitive type and consist of a rod-shaped head, a midpiece and a long flagellum. The head is about 5.15 mm in length and contains the nucleus and an apical acrosomal complex. Inside the nucleus there are three nuclear channels that begin in the subacrosomal area and have a triple helical arrangement. An nuclear fossa is present centrally, at the posterior end of the nucleus. The midpiece contains a pair of centrioles in a perpendicular arrangement, mitochondria and a narrow cytoplasmic sleeve. The flagellum has a central axoneme with a 9 + 2 pattern and two lateral projections or fins.

Ultrastructural investigations on spermatogenesis and spermatozoan morphology in the endangered Adriatic sturgeon, Acipenser naccarii (Chondrostei, Acipenseriformes)

“…In A. naccarii spermatids, a structure called the “fibrous body” appears near the implantation fossa, connecting the proximal centriole to the nucleus and extending up to the distal centriole. A similar structure was described in spermatozoa of L. osseus (Afzelius, ) and near the implantation fossa in Chondrostean species, including the starry sturgeon, A. stellatus Pallas, 1771 (Acipenseriformes: Acipenseridae) (Ginsburg, ), A. gueldenstaedtii (Dettlaff et al, ; Hatef, Alavi, Rodina, & Linhart, 2012), A. oxyrhynchus (DiLauro, Kaboord, Walsh, Krise, & Hendrix, ), A. brevirostrum , (DiLauro, Kaboord, & Walsh, ), the Chinese sturgeon, A. sinensis Gray, 1835 (Acipenseriformes: Acipenseridae), (Wei et al ), the lake sturgeon, A. fulvescens Rafinesque, 1817 (Acipenseriformes: Acipenseridae) (DiLauro, Kaboord, & Walsh, 2000), A. baerii (Pšenička et al, ), the Persian sturgeon, A. persicus Borodin, 1897 (Acipenseriformes) (Hatef et al, ), the pallid sturgeon, Scaphirhynchus albus (Forbes & Richardson, 1905) (Acipenseriformes: Acipenseridae) (DiLauro, Walsh, Peiffer, & Bennet, ), and the paddlefish Polyodon spathula (Walbaum, 1792) (Acipenseriformes: Polyodontidae) (Zarnescu, ). In none of the above cases, the origin and the development of the fibrous body have been described in detail.…”

“…The ultrastructural morphology of A. naccarii spermatozoa is similar to that of other sturgeon species, such as A. stellatus (Dettlaff et al, ; Ginsburg, 1977), A. transmontanus (Cherr & Clark, ); A. gueldenstaedtii (Dettlaff et al, , Hatef et al, 2012), A. oxyrhynchus (DiLauro et al, ), A. brevirostrum , (DiLauro et al, ), A. fulvescens (DiLauro, Kaboord, & Walsh, ), A. sinensis (Wei et al, ), A. baerii (Pšenička et al, ), A. ruthenus (Pšenička et al, ; Pšenička, Vancova, Koubek, Tesitel, & Linhart, 2009), A. persicus (Hatef et al, ), S. albus (DiLauro et al, 2001), P. spathul a (Zarnescu, ), and H. huso (Linhartova, Rodina, Nebesarova, Cosson, & Pšenička, ). The total length of the spermatozoon of A. naccarii (56.34 ± 5.67 µm) is similar to that of A. fulvescens (56.63 µm) (DiLauro et al, ) and of A. gueldenstaedtii (57.08 ± 0.79 µm) (Hatef et al, 2012) and is the third longest one among the investigated sturgeon species.…”

“…A similar ENCs variability was also found in A. baerii (Pšenička et al, ). Three ENCs were constantly found in A. stellatus (Ginsburg, 1977), A. transmontanus (Cherr & Clark, ), A. brevirostrum , (DiLauro et al, ), A. fulvescens (DiLauro et al, ), A .ruthenus (Pšenička et al, ), A. persicus (Hatef et al, ), A. gueldenstaedtii (Hatef et al, 2012), S. albus (DiLauro et al, 2001), H. huso (Linhartova et al, ), and P. spathul a (Zarnescu, ). Only two ENCs were found in A. oxyrhynchus (DiLauro et al, ) and three to five in A. sinensis (Wei et al, ).…”

Immunohistochemical distribution of hyperacetylated histone H4 in testis of paddlefish Polyodon spathula: ultrastructural correlation with chromatin condensation

“…P. spathula is one of the two living species of Polyodontidae, the other being the Chinese paddlefish, Psephurus gladius (Bremis et al 1997). Given the similarity of the paddlefish and sturgeon spermatozoon (Zarnescu 2005) and the presence of protamines in Acipenseridae (Kaverzneva and Rakhmatulina 1972;Yulikova et al 1974), the hyperacetylation of histone H4 might play an important role in nuclear condensation in P. spathula.…”