How is a sperm cell measured? How do they count them?

Question

How does a doctor know if sperm cells are defective?
How big are they?
If a human's is so small, how small must an ant's be?
Do they knock each other out of the way in the fight to the egg?

It seems that would be better than a 'good' microscope to see an ant's cells.
That would have to be a great microscope.
I wonder what holds the record for smallest cells?

Answer 1

I think they have them all line up single file and count off, I, 2, 3, 4, 5, so -on-and-so-forth, you get the idea. ;)

Answer 2

While sperm cells are pretty small, they can easily be seen in a microscope. One of the first things they'll look for is their general shape and appearance. They can also tell whether the sperm cells are swimming. They'll also often test what's called the "acrosome reaction". When a sperm cell reaches an egg, a bunch of enzymes have to get released that allow the sperm to enter the egg.

In order to fertilize an egg, there's basically a huge race. Many of the sperm cells never swim in the right direction. Of those that do, only a small proportion of them will find their way through the cervix and into the uterus. Of those that enter the uterus, half will swim up the wrong Fallopian tube. Of those that pick the right Fallopian tube it is really a race for the first one to get there and actually penetrate the egg. All of that is why so many sperm have to be produced each time.

As far as an ant's sperm cells, I would guess that they would be a whole lot smaller than a humans...But even those would still be visible in a good microscope.