title: The ultrastructure of amberjack (Seriola dumerilii) sperm.
abstract: Scanning and transmission electron microscopy were used to investigate the fine structure of sperm of the Mediterranean amberjack Seriola dumerilii. Each spermatozoon has an ovoid head which lacks an acrosome, a short, irregularly-shaped midpiece and a long flagellar tail. The midpiece houses eight spherical mitochondria, which are separated from the axoneme by the cytoplasmic canal. The centrioles are arranged approximately at right angles to each other. The proximal centriole lies inside, and the distal centriole outside, the nuclear fossa. The flagellum is inserted eccentrically into the head and is tangential to the nucleus, so that the spermatozoon is asymmetrical. It contains the conventional 9 + 2 axoneme, shows intratubular differentiations in the A microtubules of doublets 1, 2, 5 and 6, and possesses one pair of lateral fins. On the basis of its ultrastructural organization, the amberjack sperm resembles type II sperm as defined previously, except for the presence of the proximal centriole inside the nuclear fossa. This could result from a partial rotation of the nucleus during spermiogenesis.
authors.affiliation: Dipartimento di Morfologia, Biochimica, Fisiologia e Produzioni Animali, Facoltà di Medicina Veterinaria, Università degli Studi di Messina, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Maricchiolo
authors.forename: Lucrezia
authors.initials: L
authors.lastname: Genovese
authors.forename: Rosaria
authors.initials: R
authors.lastname: Laurà
authors.forename: Valeria
authors.initials: V
authors.lastname: Micale
authors.forename: Ugo
authors.initials: U
authors.lastname: Muglia
mesh_terms: D000818:Animals; D005399:Fishes / Q000033:anatomy & histology*; D005407:Flagella / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D013094:Spermatozoa / Q000648:ultrastructure*