Mn. Dilauro et al., Sperm-cell ultrastructure of North American sturgeons. II. The shortnose sturgeon (Acipenser brevirostrum, Lesueur, 1818), CAN J ZOOL, 77(2), 1999, pp. 321-330
Citations number
44
Categorie Soggetti
Animal Sciences
Journal title
CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE
The fine structure of the sperm cell of the shortnose sturgeon (Acipenser b
revirostrum) was examined using transmission electron microscopy and select
ed metrics. The cell possesses a distinct acrosome, a defined head region,
a midpiece, and a single flagellum. The mean length of the sperm cell body
(acrosome + nucleus + midpiece) is approximately 9.71 mu m, and the length
of the flagellum is about 37 mu m, resulting in a total cell length of abou
t 46 mu m. The sperm cell of the shortnose sturgeon is much longer and slig
htly wider than that of the Atlantic sturgeon. The nuclei of shortnose, whi
te, and stellate sturgeon sperm cells are elongate trapezoids with the ante
rior (acrosome) end narrowest, the opposite of that of the Atlantic sturgeo
n. Although slightly smaller in total length and width than the sperm cells
of the stellate and white sturgeons, that of the shortnose sturgeon is mos
t similar to them in overall ultrastructure, as all three cells have three
endonuclear canals. A structural connection of unknown function between the
nuclear fossa and the proximal centriole, which is similar to the fibrous
body in other species, is present in the shortnose sturgeon sperm cell. Our
results suggest a more recent evolutionary link between the shortnose, whi
te, and stellate sturgeons than between any of these and the Atlantic sturg
eon. This is the first description of sperm cell ultrastructure in the shor
tnose sturgeon, an endangered species.