Researchers can now determine if newly-fertilized mouse eggs will produce healthy offspring simply by observing them. Their findings may have implications for improving the rate of conception in couples undergoing in vitro fertilization, many of whom can only afford to perform the expensive procedure once or twice.
In the study, which is published in the current issue of Nature Communications, researcher Magdalena Zernicka-Goetz and her colleagues used high-speed photography to observe the activity inside newly fertilized mouse eggs.
What they discovered was that immediately following fertilization (entry of sperm into the egg), the cellular innards of the egg would begin to pulse rapidly, and that the pulsing motion was directed towards the spot where the sperm had entered the egg. In this image, the arrows indicate the direction of the intracellular pulses.
Amazingly, the researchers found that the speed and direction of these pulses were associated with the egg's reproductive success; by observing these pulses starting immediately after fertilization, the researchers could predict within a matter of hours whether an egg would be viable.
Zernicka-Goetz says that she and her colleagues have observed the same pulsing motions in human eggs, but have yet to see if a similar relationship between pulsing and embryo viability exists. If such a relationship were found, doctors could use the movements to dramatically improve the success rate of in-vitro fertilization.
Andrew La Barbera, scientific director for the American Society for Reproductive Medicine, found the paper compelling, but remains wary of the predictive potential of such observations in humans, pointing out that human couples have far more genetic diversity than the mice used in the research.
"This study has great promise," he said. "It remains to be seen how well these results can be translated into humans."