Researchers at Northwestern University have made a stunning discovery that gives new insights into the moment of conception. Using cutting-edge technology, those researchers have been able to look at the very moment a sperm fertilizes an egg, and the results are literally explosive.
An interdisciplinary research team at Northwestern University (h/t: Science Alert) has been using some truly cutting-edge tech to solve a mystery that has fascinated biologists for some time: how exactly does a just-fertilized egg produce the flood of zinc that is released when it successfully connects with a sperm cell?
To back up a bit, the team’s report, published in Nature, notes that the “zinc sparks” that shortly follow fertilization are “necessary to induce the egg-to-embryo transition.” It is the embryo that implants in a mammalian mother’s womb, and the explosion of zinc is a crucial step in the development of an egg into an embryo. Where does that zinc come from, though?
The team discovered that “the zinc spark arises from a system of thousands of zinc-loaded vesicles, each of which contains, on average, a million zinc atoms.”
“On cue, at the time of fertilization, we see the egg release thousands of packages, each dumping a million zinc atoms, and then it’s quiet,” said Thomas V. O’Halloran, one of the study’s corresponding authors. “Then there is another burst of zinc release. Each egg has four or five of these periodic sparks. It is beautiful to see, orchestrated much like a symphony.”
The team managed to get this close-up look at the incredible microscopic process by developing a number of new imaging techniques, using a custom-designed electron microscope and high-energy x-ray imaging technology. That allowed them to precisely map the location of zinc atoms in the cell.
The result is more than just a stunning video, though; the researchers say that their findings have implications for the improvement of in vitro fertilization techniques. The thinking is that zinc could be an indicator of healthier cells, and identifying fertilized cells with higher zinc content could lead to fewer cells needing to be implanted.
“If we can identify the best eggs,” said Theresa K. Woodruff, one of the study’s authors, “fewer embryos would need to be transferred during fertility treatments. Our findings will help us toward this goal.”