During the process of fertilization, a sperm first navigates through a cellular layer X, then binds to a non-cellular layer Y, and finally crosses a narrow gap Z before fusing with the oolemma. Identify X, Y, and Z.

Step-by-step solution

During fertilization, the sperm must penetrate the protective layers surrounding the ovum to reach its plasma membrane (oolemma). First, the sperm navigates through the outermost cellular layer, which is the corona radiata (X). Next, it binds to and penetrates the zona pellucida (Y), a non-cellular glycoprotein layer. Finally, before fusing with the oolemma, the sperm crosses the perivitelline space (Z), which is the narrow gap between the zona pellucida and the plasma membrane. Therefore, X is the corona radiata,