title: Postovulatory ageing induces structural changes in the mouse zona pellucida.
abstract: The structure of the zona pellucida (ZP) was analyzed in mouse oocytes collected soon after ovulation and in others retrieved 20 h after. The conventional methods for electron microscopy and the alcoholic PTA staining procedure which preferentially contrasts lysine-rich proteins were employed. The ZP of aged oocytes showed several structural changes which were particularly observed after using the PTA procedure. In 82.14% of the aged oocytes the ZP appeared clearly composed of two different regions: an inner dense and an outer of low density. The ZP showed a fibrillar banded structure with a parallel arrangement of fibrillar threads in both the outer and inner regions. The in vitro fertilization analysis showed that only 16.85% of the aged gametes attained the two cell embryo stage in comparision to 66.93% shown by the freshly ovulated eggs. The non-fertilized oocytes showed that no sperm penetration through the ZP occurred.
authors.affiliation: Center of Biological Investigations (CSIC), Madrid, Spain.
authors.forename: H
authors.initials: H
authors.lastname: Díaz
authors.forename: P
authors.initials: P
authors.lastname: Esponda
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D005260:Female; D005307:Fertilization in Vitro; D008183:Luteal Phase / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D046529:Microscopy, Electron, Transmission; D009865:Oocytes / Q000502:physiology / Q000648:ultrastructure*; D015044:Zona Pellucida / Q000502:physiology* / Q000648:ultrastructure*