The zona pellucida in humans contains four kinds of proteins. (sciencemag.org)
Human sperm adhered to the mouse zona pellucida if it contained human ZP2 but not if it carried human ZP3, confirming the importance of ZP2. (sciencedaily.com)
The team also tested the binding of human sperm to mouse eggs surrounded by a zona pellucida harboring human glycoproteins. (sciencedaily.com)