It’s Alive

April 16th, 2011 § 8 comments

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.

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§ 8 Responses to It’s Alive"

  • Michael Wong says:

    Hi, just wondering if you want to exchange links with me? If yes, just leave me a comment at

    I’ll link to you first, then you can link back ok? If no, that’s cool too. Have a great day!

    Cheers, Michael

    • maledoc says:

      Happy to, Michael. Although your blog isn’t about male reproduction, it’s about blogging, and some readers may find that useful.

  • Michael Wong says:

    Hi Craig,

    Thank you for approving the comment. It was very kind and generous of you despite as you say, my blog having nothing to do with male reproduction. Er…though in my very first post I did mention the word “penis” but I suspect that doesn’t qualify does it? hehe. As for myself, I’m not getting younger so I suspect it will just be a matter of time when I will find such topics personally relevant, in which case I’ll just follow the link on my blogroll to read your interesting and useful articles.


  • Yasser Ahmed says:

    Hi you mentioned that the only way to know if dna of sperm is good or not is by inserting it into an egg so a dead sperm with weak dna can fertilize the egg? Or only good dna sperm fertilize the egg?

    • maledoc says:

      I wouldn’t say that DNA can be “weak”… The way I think about it is that DNA, the molecule that is the one unique blueprint for every cell in a person’s body, is packaged carefully inside of a sperm head, and there’s a theory that packaging can be incomplete or broken. We don’t have a reliable and understandable test yet to measure that packaging and leave the sperm unharmed. Follow me on Twitter

  • Yasser Ahmed says:

    Thanks for your reply. My wife had icsi last year where her eggs were inserted with my sperm and they were fertilized and inserted into my wife but still pregnancy still didnt happen but does that mean my sperm dna was damaged?

  • Yasser Ahmed says:

    In other words can a sperm with damaged or incomplete dna ever fertilize an egg?