Some couples are unable to conceive because the woman's eggs screen his sperm for DNA quality and give it a thumbs down, the Independent reports. Scientists in Britain and the US have spotted this "lock-and-key" mechanism in which eggs "read" sperm's DNA, most of which is tightly packed inside. If tests are developed, this research could help couples understand their infertility and ensure the success of vitro fertilizations.
The research also shows that sperm does more than send DNA to the egg to be regulated and controlled by the mother's DNA. By revealing some DNA for an "open confirmation," the sperm plays a greater role in developing the embyro. "It contradicts the dogma that the egg does everything," one scientist says.