That's the egg, and we all know how this story goes.

Sperm

So we start with a zygote. This is a fertilized egg.

Just as an aside, this unification, this fertilization that occurred from this sperm cell to this egg cell, so it essentially penetrates into this egg cell and it creates this zygote, which is a fertilized egg cell from my mother, and this contains all DNA from both my father and my mother.

And it's now ready to essentially turn into an organism.

So this very first cell that was created from this fertilized egg, this is called a zygote.

So that very first cell that was essentially my mom's egg fertilized by a sperm cell from my father, that was a zygote, and as soon as it's successfully fertilized, it has 2N, or it has the diploid number of chromosomes in the case of humans, which I believe I am one of them.

Baby's first division

It's the females, I think, that lay the eggs, and then the males fertilize them.

Let me do that Y chromosome in a separate color.

My father's sperm somehow met my mother's egg, and they fused.

female eggs were to be fertilized in a lab and given a cocktail of growth hormones.

It's our own pond. And that's how it happens.

And this is where the system gets really interesting.

But now with some of this vocabulary thrown out of the way, let's talk a little bit about zygotes and how do zygotes turn into people, and then how do those people essentially produce gametes, which then can fertilize other people's gametes to form more zygotes.

The focus of this video is how this fertilized egg develops once it has become a zygote.

...in unfertilized emu or ostrich eggs.

So we were inspired by the oyster, but I was also inspired by the life cycle of the oyster.

As soon as the sperm fertilizes this egg, now, all of a sudden, you have a diploid zygote.

So now let me pick a nice color.

If the queen uses the stored sperm to fertilize an egg, then that egg will grow up to become female.

Fuck.

For each homologous pair, I'm either going to contribute the one that I got from my mother or the one that I got from my father, right?

So, ant colonies are a good example of an organization like that, and there are many others.

Some people who have XX chromosomes develop what are called ovotestis, which is when you have ovarian tissue with testicular tissue wrapped around it.

It's not just any cell in the body.

Let me draw the sperm.

But even this process of fertilization is an incredibly competitive process, because this sperm that happened to be the one that kind of won the race from my father to fertilize my mother's egg, it was actually the first of roughly 200 million other sperms.

They actually perform a surgery, take them out of the ovaries of the mother, and then they fertilize them with semen, either it might come from the father or a sperm donor, so then all of these becomes zygotes once they're fertilized with semen.

Now, in the case of humans, the diploid number is 46, so N is equal to 23.

I need to ask you to return with me to the beginning where each of us began.

So that's a gamete and this is a gamete.

In some cases, another species like the North American Leopard Frog showed that males exposed to atrazine grew eggs in their testes.

And I'll draw the sperm much larger than it is normally relatively to the egg.

The walls of the egg then become impervious to other sperm so that only one sperm can get in, but that's not the focus of this video.

Where we left off after the meiosis videos is that we had two gametes.

Oeufs. Un oeuf, des oeufs.

What if you could change the sperm and the ova, or change the newly fertilized egg, and give your offspring a better chance at a healthier life eliminate the diabetes, eliminate the hemophilia, reduce the risk of cancer?

Unlike a normal frog, which lays its eggs in the water and goes away and wishes its froglets well, this frog swallowed its fertilized eggs, swallowed them into the stomach, where it should be having food, didn't digest the eggs, and turned its stomach into a uterus.

Meet the hermaphrodites.

So actually, let me just kind of simplify things a little bit because we don't have to start here.

Men, through their penis, they fertilize the eggs by the sperm coming out.

So this is diploid, and it's a zygote, which is just a fancy way of saying the fertilized egg.

And it's really an odd sort of structure.

We're visited by Dr, Dervaux. a psychiatrist,