What physiological reaction prevents polyspermy (fertilization of an ovum by more than one sperm)?
Answer and explanation
Correct answer: D. The cortical reaction: exocytosis of cortical granules that enzymatically harden the zona pellucida
Upon sperm-egg membrane fusion, a wave of intracellular Ca2+ sweeps through the oocyte, triggering the cortical reaction. Cortical granules beneath the oolemma release enzymes via exocytosis that cleave ZP3 receptors and cross-link glycoproteins in the zona pellucida (the zona reaction), establishing a permanent slow block that prevents entry of additional sperm.
Practise more Immunology, Renal Excretion, Reproduction, and Human Genetics.
Free questions with an explanation for every one, and full timed Toelatingsexamen Arts & Tandarts België (Medical & Dental Entrance Exam) mock tests.
More Immunology, Renal Excretion, Reproduction, and Human Genetics questions
- Which characteristic distinguishes adaptive (acquired) immunity from innate immunity?
- Which cells function as professional antigen-presenting cells (APCs) capable of activating naive CD4+ T helper cells by expressing surface C…
- How do cytotoxic CD8+ T lymphocytes recognize foreign antigens on the surface of target cells?
- During T-cell development in the thymic cortex, what is the outcome of positive selection?
- Which structural region of an antibody molecule determines its antigen-binding specificity?
- Which immunoglobulin isotype is the first to be secreted in significant quantities during a primary humoral immune response to a novel patho…