New discovery reveals how the egg controls sperm entry
After the egg has been fertilized by a sperm, the surrounding egg coat tightens, mechanically preventing the entry of additional sperm and the ensuing death of the embryo. This is according to a new study led by researchers at Karolinska Institutet and published in the journal Cell. The work also explains how mutations in egg coat proteins can cause female infertility and may eventually lead to new contraceptive methods.Fertilization in mammals begins when a sperm attaches to the egg coat, a filamentous extracellular envelope that sperm must penetrate in order to fuse with the egg. Now an