Here's why:
* Meiosis: Female germ cells undergo meiosis, a process of cell division that reduces the number of chromosomes by half.
* Unequal division: Meiosis in females is characterized by unequal division of cytoplasm. One daughter cell receives most of the cytoplasm, becoming the egg cell. The other three daughter cells receive very little cytoplasm and become polar bodies.
* Polar bodies: Polar bodies are essentially non-functional and eventually degenerate. They exist to ensure the egg cell receives the majority of the genetic material and resources.
So, while the starting point is one germ cell, only one functional gamete (the egg) is formed.
