FORGET tall, dark and handsome – smooth, oval and symmetrical is what an egg wants in sperm. Now it seems that the sperm chosen on these grounds to use in assisted reproduction are more likely to carry an X chromosome than a Y.
Couples struggling to conceive may opt for a technique that involves extracting the woman’s eggs and injecting each with a sperm, chosen after examining them at either 400x or 6600x magnification.
Daniela Braga at the in São Paulo, Brazil, examined 153 embryos fertilised using the lower magnification technique and 240 using higher magnification. She…
