ReCGiP: Database of Reproduction Candidate Genes in Pigs based on bibliomics

Fertilization

Fertilization is the process of the union of the sperm and the egg. After the sperm has cut through the first layer surrounding the egg that is the corona radiate, a multicelluar layer using sperm motility, it encounters the zona pellucida. Through an acrosomal reaction, hydrolase enzymes released from the sperm digest a path through the layer. Then the sperm encounters the most inner layer of the egg coverings, the plasma membrane. Sperm receptors on the surface of the egg plasma membrane bind directly to the sperm. These two surfaces fuse and the sperm moves into the egg. When the sperm enters the egg, the sperm nucleus, now highly compacted chromatin material, decondenses and forms the male pronucleus. At the same time, the meiotic arrest is lifted for the egg, and it completes its second meiotic division. It creates another polar body and the female pronucleus. DNA replication occurs in each site. Once they come together, the membranes degenerate and the contents of the pronuclei are allowed to mix along a single spindle, forming one cell.