Oogenesis

What is Oogenesis?

The process of female gamete production

Where does Oogenesis occur?

the ovaries of female organisms.

At what stage does Oogenesis begin?

during fetal development.

What is a primary oocyte?

an immature female gamete that has not completed meiosis.

What is oogonium

diploid germ cell in the ovary that can develop into two primary oocytes using mitosis

What is a polar body?

a haploid byproduct of Oogenesis formed at the same time as an egg cell that cannot be fertilized.

How many primary oocytes does a female fetus have after 3 months?

Two million

What happens to primary oocytes?

begin meiosis before the fetus is born, but stalls in prophase I, until puberty

What happens after puberty?

Every month after puberty, one primary oocytes begins meiosis.

How is a secondary oocyte made?

After meiosis I, cytoplasm is not equally divided between two daughter cells. The cell with the most cytoplasm is the secondary oocyte.

How does Oogenesis differ from Spermatogenesis?

Oogenesis results in one viable egg and polar bodies, while spermatogenesis results in four viable sperm.

How is a Ovum (egg) formed?

Secondary oocyte undergoes meiosis II, cytoplasm is again unequally divided. Cell with the most cytoplasm eventually becomes a mature egg (ovum)

Why may some ova not form?

A secondary oocyte is released down fallopian tube, and pauses at Metaphase II until it comes into contact with a sperm.

What is meiosis I and II in Oogenesis?

Meiosis I produces a secondary oocyte, and meiosis II is completed only if fertilization occurs.