title: Comparative ultrastructure of spermatozoa of the redclaw Cherax quadricarinatus and the yabby Cherax destructor (Decapoda, Parastacidae).
abstract: Ultrastructure of spermatozoa of redclaw Cherax quadricarinatus and yabby Cherax destructor were described and compared. The acrosome complex and nucleus are located at the anterior and posterior region of the spermatozoon, respectively. The acrosome is a complex vesicle divided into two parts: the main body of the acrosome appears as a dense cup-shaped structure in longitudinal sagittal view, with the subacrosome zone occupying the central area of the vesicle. The acrosome is larger in C. quadricarinatus (width 2.37±0.27μm, length 1.31±0.23μm) than in C. destructor (width 1.80±0.27μm, length 1.01±0.15μm). There was no significant difference in L:W ratios of the studied species. The subacrosome zone in both species consists of two areas of different electron density. The nucleus is substantially decondensed and irregular in shape, with elaborate extended processes. The examined species exhibited a well-conserved structure of crayfish spermatozoon, similar to those of Cherax cainii and Cherax albidus. Small acrosome size, the absence of radial arms, and an extracellular capsule seem to be the morphological features that mostly distinguish Cherax from the Astacidae and Cambaridae.
authors.affiliation: University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, CZ-389 25 Vodňany, Czech Republic. Electronic address: akouba@frov.jcu.cz.
authors.forename: Antonín
authors.initials: A
authors.lastname: Kouba
authors.affiliation: University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, CZ-389 25 Vodňany, Czech Republic.
authors.forename: Hamid
authors.initials: H
authors.lastname: Niksirat
authors.affiliation: University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, CZ-389 25 Vodňany, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Bláha
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D033364:Decapoda / Q000648:ultrastructure*; D008297:Male; D046529:Microscopy, Electron, Transmission; D013094:Spermatozoa / Q000648:ultrastructure*
keywords: Acrosome; Crayfish; Decapoda; Spermatozoon; Transmission electron microscopy