1.2.2.1.3.1. Zygote Development

Let's start our exploration of zygote development by discussing fertilization. What happens during this phase?

Isn't it when the sperm and egg come together?

Exactly! This fusion forms the zygote. There are two types of fertilization: internal and external. Can anyone give an example of each?

Fish and frogs have external fertilization, right?

Correct! And humans have internal fertilization. Let’s remember: Internal = Inside; External = Outside. Now, what then happens to the zygote?

It starts dividing?!

Yes! This process is known as cleavage. Great job! We'll talk more about that next.

Now, after the zygote is formed, it undergoes cleavage. Can anyone tell me what cleavage involves?

It divides into smaller cells, right?

Exactly! These smaller cells are called blastomeres. This continues until we reach the morula stage, a solid ball of cells. Who can explain what a morula looks like?

I think it looks like a mulberry!

Perfect! That’s an excellent memory aid. Remember, morula = mulberry. Can anyone guess what happens after the morula stage?

It becomes the blastula?

Yes! The transformation into the blastula is a key transition. Let’s summarize what we've learned so far.

Now, let’s move on to the blastula. What features define this stage, and what comes next?

It has a fluid-filled cavity, right?

Correct! That cavity is called the blastocoel. After the blastula, we enter gastrulation. Does anyone want to explain what happens during this process?

It forms three layers, like ectoderm, mesoderm, and endoderm, which turn into all the different organs!

Exactly! This process is essential for proper organism development. It’s like laying down the foundation for a building. Let’s summarize what we have learned about the stages.