What is the developing structure called when the zygote divides and forms groups that develop into different tissues and organs?

The developing structure is called an Embryo when the zygote divides and forms groups that develop into different tissues and organs.

Here are the steps:

1. Fertilization: The process begins with the fusion of an egg and sperm, forming a zygote.

2. Cleavage: The zygote then starts to divide through a process called cleavage. This is a series of rapid cell divisions without growth.

3. Blastula Stage: After several rounds of cleavage, a hollow ball of cells called a blastula is formed.

4. Gastrulation: The blastula then undergoes a process called gastrulation, where it reorganizes itself into a three-layered structure called a gastrula. These three layers are the ectoderm, mesoderm, and endoderm.

5. Organogenesis: These three layers then develop into different tissues and organs in a process called organogenesis, forming an embryo.

So, the developing structure when the zygote divides and forms groups that develop into different tissues and organs is called an Embryo.