Molecular discovery reveals how chromosomes are passed from one generation to the next

When a woman becomes pregnant, the outcome of that pregnancy depends on many things—including a crucial event that happened while she was still growing inside her own mother's womb. It depends on the quality of the egg cells that were already forming inside her fetal ovaries. The DNA-containing chromosomes in those cells must be cut, spliced and sorted perfectly. In males, the same process produces sperm in the testes but occurs only after puberty.