* Sperm digest a small hole in the zona pellucida through which it can pass. This small,regional dissolution leaves the zona predominantly intact. Maintainence of the zona is important to prevent blastomeres in the early embryo from separating. | * Sperm digest a small hole in the zona pellucida through which it can pass. This small,regional dissolution leaves the zona predominantly intact. Maintainence of the zona is important to prevent blastomeres in the early embryo from separating. |