21. Filled with uterine fluid, the blastocyst breaks out of the zona pellucida and undergoes implantation. 22. Once the sperm cells find their way past the zona pellucida , the cortical reaction occurs. 23. In 24 to 48 hours, the zona pellucida breaches. 24. N-acetylglucosamines on the zona pellucida normally promote sperm binding. 25. In mammals, however, the extracellular matrix modified by the cortical reaction is the zona pellucida . 26. ZP3 is the receptor in the zona pellucida which binds sperm at the beginning of fertilization. 27. ZP3, a glycoprotein in the zona pellucida , is responsible for egg / sperm adhesion in mice. 28. During the freezing process, the zona pellucida , or shell of the egg can be modified preventing fertilization. 29. The zona pellucida ( ZP ) is a specialized extracellular matrix that surrounds the oocyte and early embryo. 30. Porcine zona pellucida has its critics.
