At fertilization, spermatozoa bind to the zona pellucida (ZP1, ZP2, ZP3)surrounding ovulated mouse eggs, undergo acrosome exocytosis and penetrate the zona matrix before gamete fusion. Following fertilization, ZP2 is proteolytically cleaved and sperm no longer bind to embryos. We assessed Acr3-EGFP sperm binding to wild-type and huZP2 rescue eggs in which human ZP2 replaces mouse ZP2 but remains uncleaved after fertilization. The observed de novo binding of Acr3-EGFP sperm to embryos derived from huZP2 rescue mice supports a `zona scaffold'model of sperm-egg recognition in which intact ZP2 dictates a three-dimensional structure supportive of sperm binding, independent of fertilization and cortical granule exocytosis. Surprisingly, the acrosomes of the bound sperm remain intact for at least 24 hours in the presence of uncleaved human ZP2 regardless of whether sperm are added before or after fertilization. The persistence of intact acrosomes indicates that sperm binding to the zona pellucida is not sufficient to induce acrosome exocytosis. A filter penetration assay suggests an alternative mechanism in which penetration into the zona matrix initiates a mechanosensory signal transduction necessary to trigger the acrosome reaction.
The Company of Biologists Workshops
For the last 15 years, our publisher, The Company of Biologists, has provided an apt environment to inspire biology and support biologists through our Workshops series. Read about the evolution of the Workshop series and revisit JEB's experience with hosting the first Global South Workshop.
Call for papers – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues
Development invites you to submit your latest research to our upcoming special issue – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues. This issue will be coordinated by Guest Editors Meritxell Huch (Max Planck Institute of Molecular Cell Biology and Genetics, Germany) and Mansi Srivastava (Harvard University and Museum of Comparative Zoology, USA), working alongside our team of academic Editors. Submit your articles by 30 May 2025.
Meet our 2025 Pathway to Independence (PI) fellows
We are delighted to announce our third cohort of PI fellows - researchers whom we will be supporting as they transition from postdoc to Principal Investigator. Read about the eight talented fellows chosen, whom we're excited to be working with as they navigate the job market.
A case for broadening our view of mechanism in developmental biology
In this Perspective, B. Duygu Özpolat and colleagues survey researchers on their views on what it takes to infer mechanism in developmental biology. They examine what factors shape our idea of what we mean by ‘mechanism’ and suggest a path forward that embraces a broad outlook on the diversity of studies that advance knowledge in our field.
the Node: Have your say
Our community site, the Node, is conducting a user survey about the content and the design of the site. Help us shape the Node's future and thank you for being a part of the Node over the last 15 years.
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