The traditional view, called the "acrosome reaction," argues that a calcium spike triggers the acrosome to expel its enzymes in an "all or nothing" manner, like popping a water balloon ...

The acrosome must work correctly for the sperm to penetrate the egg coating (or zona pellucida). After the acrosome reaction, the sperm reveals binding sites that it needs to fuse to the egg. The ...

Of interest, when Epel's group inhibited this acrosome reaction using chemicals, the sperm no longer made a lot of NO. So this reaction seems crucial for NO production in the sperm. Eggs ...