It was long thought that during an embryo’s first cell division, one spindle is responsible for segregating the embryo’s chromosomes into two cells. Scientists now show that there are actually two spindles, one for each set of parental chromosomes, meaning that the genetic information from each parent is kept apart throughout the first division.
The beginning of life
Furthermore, the knowledge from this paper might impact legislation. In some countries, the law states that human life begins – and is thus protected – when the maternal and paternal nuclei fuse after fertilization. If it turns out that the dual spindle process works the same in humans, this definition is not fully accurate, as the union in one nucleus happens slightly later, after the first cell division.