After last week’s post about pus in semen, I thought that it might be helpful to describe another important sperm test, one that shows whether or not they’re alive.
Good sperm are alive. Not only do they swim, they live and breathe just as all living cells do. Some are dead, meaning that the ship is no longer sailing, and its motor and crew are gone.
One way of figuring out whether or not sperm are alive is to dip them in colored dye. A dead sperm can’t push the dye out of its body, but a live sperm can. In the picture, the sperm are stained with a pink dye called Eosin. The dead sperm are the ones that become pink, and the live sperm are the ones that push the dye outside and stay clear (a light bluish green in the photograph.)
The result of the test is typically described in the percentage of sperm that are alive, and of course, the more living sperm the better. But even when all of the sperm are dead, a condition called “necrospermia”, couples can still conceive using in-vitro fertilization with intra-cytoplasmic sperm injection.
That doctors can successfully use dead sperm with in-vitro fertilization illustrates a conundrum in reproductive medicine today. The ultimate barrier to fertilization is no longer the entire sperm’s health, but the quality of its DNA cargo. Unfortunately, we don’t yet have a way of knowing the condition of a single sperm’s DNA before inserting that sperm into an egg.
So if a man’s sperm don’t wiggle, the first thing to know is whether they’re alive and sluggish or whether they’re dead. A vital stain makes that distinction. But if they’re dead, a man shouldn’t despair. Dead sperm can still be used in intra-cytoplasmic sperm injection as long as their DNA is good. Unfortunately, the only way to know that right now is to inject the sperm and to see what happens.