IBBEA   24401
INSTITUTO DE BIODIVERSIDAD Y BIOLOGIA EXPERIMENTAL Y APLICADA
Unidad Ejecutora - UE
capítulos de libros
Título:
Spermatogenesis and Sperm Morphology
Autor/es:
GIM√ČNEZ, J.
Libro:
Spawning Biology, Sexual Strategies and Ecological Effects.
Editorial:
Nova Sciense Publishers
Referencias:
Lugar: Hauppauge, New York.; Año: 2014; p. 49 - 72
Resumen:
This study describes the revision of spermatogenesis and paraspermatogenesis process in gastropods and comparative sperm morphology in the most of the classes of Molluscs.                         The spermatogenesis pattern including, the nuclear condensation involved granular, fibrillar, lamellar, and final homogenous electron-dense phases. Acrosome development starts with the posteriorly-located proacrosomal vesicle arising from the Golgi complex in euspermatids. This proacrosomal vesicle develops into a pre-attachment acrosome, which, together with the Golgi body, later moves towards the apex of the nucleus.  Ultrastructural studies show that spermatozoa are useful indicators of systematic position and phylogenetical relationship within the Molluscs. The morphology of the mature sperm of Bivalves, Solenogasters, Monoplacophora, Cephalopoda and Gastropoda, given in this work, can be used to understand some aspect of the reproduction, how the shape of the sperm can be related to internal or external fertilization. Also is describes the dimorphic types of sperms in gastropods, call parasperm, and this related to the mode and the capacity of fertilization and the morphology of the parasperm also can be used as indicators of systematic position. Paraspermatogenesis is describes in gastropods and the pattern of chromatin distribution in dense patches, together with the cytoplasmatic characteristics of paraspermatogonia, allow for the recognition of the apyrene line from the euspermatogonia. Later-occurring features, including the peripheral condensation of nuclear chromatin followed by nuclear invagination, the posterior breakdown into nuclear vesicles (?caryomerites?), centriole multiplication, and the synthesis of secretory products, are the most conspicuous changes in the paraspermatogenesis process.