This video is taken from Prof Homer’s recent publication in the prestigious journal, Nature Communications. It depicts a high-resolution time-lapse movie filmed using confocal microscopy of an egg undergoing maturation. The spindle is the machinery that cells use to share genetic material (that is packaged within structures called chromosomes) when a cell divides. In the movie, the spindle is shown in green and the chromosomes appear yellow.
Prof Homer’s team discovered that after chromosomes begin separating in eggs, the spindle lunges forward and causes the outer egg surface to protrude. Ultimately, this leads to the formation of one very small cell (called a polar body) and one very large cell (the egg). In this way, the egg is able to retain all the “nutrients” it requires for supporting pregnancy after becoming fertilised by sperm. This mechanism that Prof Homer discovered is therefore critical for achieving a successful pregnancy.