if vaginas are self cleaning organs, and constantly outflowing acidic fluids- how in the world does sperm swim against the current to impregnate someone?


Does the semen’s alkalinity deactivate it? How is something so small able to swim against the current in tight tissues?

In: 21

Have you ever heard of the dreaded Condiru? This nasty little fish has a penchant to swim up a man’s urethra while peeing into the Amazon.

My swimmers can navigate some slow flow.

It’s not like there’s a swift-moving river up there. More like a slow, steady stream. And the sperm have their tails to swim upstream faster, like salmon swimming up a stream. Most don’t make it, but there are a lot of them.

Several things matter here, but

1 sperms are very strong swimmers.

[If you look at the ratio of the tail to the head on a single sperm cell](https://images.pond5.com/circular-movement-single-sperm-cell-footage-201192684_iconl.jpeg) that’s kind of a rocket ship. Or a fighter jet. Right? Its a whole lot of propulsion relative to the payload it has to move. In fact, of all the various medical issues that can cause a man’s sperm to be not-effective, one of the things they look for are physically dysfunctional swimmers. “sperm motility” = are your swimmers actually swimming.

2 there’s a lot of them. Yes, that acidic environment is going to kill off some of them. But there’s millions of them and only one needs to make it.

3 its hydrophobic. It doesn’t mix well with other fluids. What that means is the ejaculate mix clumps up instead of spreading out and mixing with some other fluid (like bodily fluid).

Imagine 300 sperm cells are like 300 spartan soldiers. Now, imagine all that vaginal fluid is like the enemy, trying to stab and kill all those 300 spartans.

Now, if all the spartan sperm soldiers are just floating around loosely, and the enemy fluid is able so mix in and get to all of them, they can easily kill them all right?

[BUT, what if the spartan sperm troops all clump together in a tight formation?](https://bpb-us-e1.wpmucdn.com/sites.psu.edu/dist/2/10736/files/2014/04/00006081.jpg)

You’re still gonna get to all the guys on the outside edges, but its gonna be tough getting at the guys in the middle right? Cause they’re protected by the layers of guys around them. Similar idea. The ejaculate fluid clumps up and doesn’t mix well with the vaginal fluid, which helps act a a layer of shield against the hostile fluid, and then the whole sperm army of millions packed into its little sperm phalanx can spare a few ranks of troops on the edges, but SOMEONE will survive long enough to invade the egg kingdom

Accuracy by volume. The sheer number of sperm dumped in there is mind boggling, most of them don’t make it.

A woman’s reproductive tract varies in acidity. During ovulation it becomes less acidic and the cervical mucus thins to make it easier for sperm to enter. While the vagina is acidic, the cervix and womb are much friendlier to sperm. The walls of the womb contract and ripple to help the sperm reach the fallopian tubes. The fluid in the tube further helps sperm, providing it with a nutrient boost to help it on the final leg of it’s journey.