I’m talking about humans specifically here. During school I was always shown animations that showed many sperm swimming to an egg, and then when the first sperm started entering the egg (don’t even know how they do that, do they eat through?), the other sperm just stopped trying and gave up. How do the other sperm know? Are they sentient? What’s stopping loads of sperm going into the same egg? What would happen if 100 sperm went into the egg at once?
In: Biology
They don’t know anything. But they don’t have to. When the first sperm penetrates the egg cell, it causes a chemical reaction in the membrane that makes it impossible for further sperm cell to also successfully penetrate. They will keep trying but eventually they will just die.
As soon as one sperm bonds with the ovum, a chemical process occurs that make the outside impermeable to all the others, effectively instantly. We think there might be a chemical ‘homing beacon’ being sent by the egg prior to this, but there’s no real certainly of that currently.
Generally, competition isn’t a problem, as only a few hundred out of several hundred *million* sperm will actually make the journey all the way there. But if it does happen, cell division cannot occur, and the cell just dies.
The sperm that successfully fertilizes the egg merges with it very quickly. The egg the. Begins to release chemicals that stop other sperms from entering.
What then happens with all those other sperms? They all die out in the fallopian tubes if they hadn’t already died in the journey to the egg
They don’t know, they don’t give up.
When the first sperm enters the egg successfully, the egg creates a layer around itself which prevents additional sperm from entering. The sperm keep trying but they can’t get through that membrane.
The very rare (in humans) case where two or more sperm fertilize an egg at the same time, before the membrane can be created to prevent subsequent sperm getting through, usually results in the death of the egg.
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~~ From what I’ve heard, it’s the egg that let’s in the sperm ~~
~~ So technically, it might not be the first sperm that reaches the egg. ~~
~~ I also have no justification to this, so maybe someone who knows can explain? ~~
Edit: I did some research
https://www.news-medical.net/news/20200611/The-egg-decides-which-sperm-fertilizes-it.aspx
From what’s stated, it’s not the egg choosing the specific sperm, but rather, sperm from a specific mate.
My bad.
Also, I believe this is just one study.
They don’t. Sperm swim until they run out of energy and die. Once the egg is fertilized, it rapidly forms a layer that blocks addition sperm from entering the egg, perhaps that’s what you are thinking about?
I saw a little documentary called The Great Sperm Race that went into detail about the whole process.
sperm have to find a key to let them through the shell first. the first one to enter immediately triggers a wave that removes all other keys from outside the wgg
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