Microsort has been sorting human sperm by sex for years. By isolating X-chromosome bearing sperm (which create sugar-and-spice girls) from Y-chromosome bearing sperm (which creates puppy dog tails, er, boys), the company produced its first selected-sex success story in 1996: Jessica Collins. Since then, they’ve offered their X-linked genetic disease prevention services and their family balancing services to over 300 couples so far. Their technique is based on the fact that X chromosomes are bigger than Y ones, so sperm containing them have around 3% more DNA – and therefore weight. The slightly heavier “girl” sperm can be separated from their sleeker “boy” competition using a flow cytometer – not exactly the environment the sperm had hoped to find themselves in, to be sure. Around 85% of Microsort’s customers use the technique strictly for gender selection, with a success rate of 90 percent for producing girls and 75 percent for producing boys at $2300 a pop. When the company gets to 750 cases, it can seek FDA certification for the technique.
A more urgent need in fertility medicine is to separate good sperm from bad regardless of what sex child they would produce. Naturally, that’s where this month’s breakthrough in microfluidics comes in, er, handy. Michigan scientists have developed a chip that can separate the good sperm from the bad ones…but unfortunately not the ugly ones, yet. Obstetrics researcher Gary Smith hit on the idea when he heard about a curious phenomenon of fluids: microscopically narrow streams running side by side barely mix. “I thought well, gosh, this would help to sort sperm!” (For this insight, Smith gets the Geek of the Year award in my book. He hears about a fluid dynamics phenomenon, he thinks up practical sex applications. Somebody needs to explain wormholes to this guy.) A chip Smith and others developed can now take an ejaculation with only 45% motile sperm and have 98% motile sperm come out the other end – a boon for infertility treatments. Previously such treatments meant hours in a centrifuge for sperm (which left them dizzy?). Now, one pass through the Microscale Integrated Sperm Sorter yields a healthy pack of contenders that are ready for a hot night out on the town.