title: Comparative ultrastructure of the spermatozoa of three crayfish species: Austropotamobius torrentium, Pacifastacus leniusculus, and Astacus astacus (Decapoda: Astacidae).
abstract: This study reports about the spermatozoal ultrastructure of three species of astacid crayfish, i.e., the stone crayfish Austropotamobius torrentium, signal crayfish Pacifastacus leniusculus, and noble crayfish Astacus astacus. The acrosome is a cup shaped and electron-dense structure at the anterior of the spermatozoon and comprises three layers of differing electron densities filled with parallel filaments that extend from the base to the apical zone. The acrosome was significantly longer in A. astacus than in P. leniusculus and the shortest acrosome belongs to A. torrentium. The width of the acrosome was significantly narrower in A. torrentium than in P. leniusculus and the widest acrosome belongs to A. astacus. The L:W ratio was significantly greater in A. torrentium than in P. leniusculus and the lowest ratio belongs to A. astacus. Radial arms are visible on each side of the acrosome or nucleus in sagittal view and wrap around the spermatozoon. Each radial arm comprises a parallel bundle of microtubules arranged along the long axis within a sheath. The nucleus, with decondensed material, is located in the posterior of the cell. All parts of the spermatozoon are tightly enclosed within an extracellular capsule. Despite a well-conserved general structure and similarity of pattern among these spermatozoa, differences in the dimensions of the acrosome within the studied species may be useful to help distinguish the different crayfish species.
authors.affiliation: Research Institute of Fish Culture and Hydrobiology, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia in České Budějovice Zátiší 728/II, 389 25 Vodňany, Czech Republic. niksirat@frov.jcu.cz
authors.forename: Hamid
authors.initials: H
authors.lastname: Niksirat
authors.forename: Antonín
authors.initials: A
authors.lastname: Kouba
authors.forename: Marek
authors.initials: M
authors.lastname: Rodina
authors.forename: Pavel
authors.initials: P
authors.lastname: Kozák
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D003400:Astacoidea / Q000145:classification* / Q000166:cytology*; D002467:Cell Nucleus / Q000648:ultrastructure; D008297:Male; D013094:Spermatozoa / Q000648:ultrastructure*