title: Fine structure of the spermatozoa of Crassostrea gigas (Mollusca, Bivalvia).
abstract: We describe sperm ultrastructure and acrosome differentiation during spermiogenesis in Crassostrea gigas (Mollusca Bivalvia). The sperm cell is a uniflagellated cell of the primitive type. The head region contains a rounded or conical nucleus surmounted by small acrosome. This organelle consists of a membrane-bound acrosomal granule, the contents of which have a homogeneous density, except in the anterior region, which is positive for PTA. The acrosome also surrounds the perforatorium, which includes oriented fibrillar elements: this is the axial body. The middle piece contains four mitochondria encircling two perpendicular centrioles. The distal centriole is provided with a system of mechanical fixation to the plasma membrane, consisting of nine fibers in radial arrangement. The tail flagellum, about 50 microns long, contains the usual microtubular axoneme.
authors.affiliation: Department of Biochemistry and Physiology, Faculty of Biology, University of Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Gràcia Bozzo
authors.forename: E
authors.initials: E
authors.lastname: Ribes
authors.forename: E
authors.initials: E
authors.lastname: Sagrista
authors.forename: M
authors.initials: M
authors.lastname: Poquet
authors.forename: M
authors.initials: M
authors.lastname: Durfort
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D008297:Male; D010125:Ostreidae / Q000166:cytology*; D013091:Spermatogenesis; D013094:Spermatozoa / Q000648:ultrastructure*