Prophase I Mouse Oocytes Are Deficient in the Ability to Respond to Fertilization by Decreasing Membrane Receptivity to Sperm and Establishing a Membrane Block to Polyspermy1
| Autor: | Janice Perry Evans, Cassie A. Kryzak, Diane D. Kyle, Douglas N. Robinson, Caelin Cubeñas-Potts, Maia M. Moraine, Hyo J. Lee |
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| Rok vydání: | 2013 |
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| Zdroj: | Biology of Reproduction. 89 |
| ISSN: | 1529-7268 0006-3363 |
| DOI: | 10.1095/biolreprod.113.110221 |
| Popis: | Changes occurring as the prophase I oocyte matures to metaphase II are critical for the acquisition of competence for normal egg activation and early embryogenesis. A prophase I oocyte cannot respond to a fertilizing sperm as a metaphase II egg does, including the ability to prevent polyspermic fertilization. Studies here demonstrate that the competence for the membrane block to polyspermy is deficient in prophase I mouse oocytes. In vitro fertilization experiments using identical insemination conditions result in monospermy in 87% of zona pellucida (ZP)-free metaphase II eggs, while 92% of ZP-free prophase I oocytes have four or more fused sperm. The membrane block is associated with a postfertilization reduction in the capacity to support sperm binding, but this reduction in sperm-binding capacity is both less robust and slower to develop in fertilized prophase I oocytes. Fertilization of oocytes is dependent on the tetraspanin CD9, but little to no release of CD9 from the oocyte membrane is detected, suggesting that release of CD9-containing vesicles is not essential for fertilization. The deficiency in membrane block establishment in prophase I oocytes correlates with abnormalities in two postfertilization cytoskeletal changes: sperm-induced cortical remodeling that results in fertilization cone formation and a postfertilization increase in effective cortical tension. These data indicate that cortical maturation is a component of cytoplasmic maturation during the oocyte-to-egg transition and that the egg cortex has to be appropriately primed and tuned to be responsive to a fertilizing sperm. |
| Databáze: | OpenAIRE |
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