Description: This 3D medical animation shows a sperm fertilizing an egg. First, the sperm pushes through an outer layer of cells surrounding the egg, called the corona radiata. When the sperm reaches the next layer, called the zona pellucida, the sperm's head releases digestive enzymes that allow it to burrow through the zona to a narrow space just outside the egg cell membrane. The head of the sperm fuses with the egg cell membrane, and its genetic contents are pulled inside the egg.
Last Updated: Jan 20th, 2019