Fertilization

[konrad]

I have one question. where we can talk about ovum? Many people call ovum cell before fertilization. They say that is last step of ovulation.
What do you think? In my opinion we shouldn't call ovum before fertilization becauce before fertilizaction meiosis II at oocyte II is arrested in metaphase. So it is still oocyte. After ferlilization meiosis II is finished.
What is your opinion?
I hope you understand me. Sorry for my english

[baikuza]

i do not get what you want to say...

In my opinion we shouldn't call ovum before fertilization becauce before fertilizaction meiosis II at oocyte II is arrested in metaphase. So it is still oocyte. After ferlilization meiosis II is finished.

[army]

Nooooo...
It's not like that.

Let me make it clear.
Fertilization happens when a sperma nucleus meets ovum' nucleus.

So, it's quite clear that ovum cell can be called as 'ovum' before fertilization.

But, that's true if you say the oogenesis is delayed in the meiosis II, when the cell is called oocyt. But then this process is continued after a girl gets adult. So that, every month a woman produce ovum, continuing the phase of meiosis II.

This ovum will be fertilized when a sperm could reach it. But if not, ovum will be disposed together with endometrium trough the process called menstruation.

Do you get it?

[konrad]

I think meiosis II is delayed in every age.
Protein kinase called Rsk inhibits action of the anaphase-promoting complex and arrests meiosis in metaphase II until fertilization.
Before fertilization you even dont' have socond polar body.
In fallopian tube oocyte is fertilized by sperm. During the fertilization, receprors on the envelpoe of secondary oocyte gets signal from sperm. This signal gives rise to increase in level of Ca2+(in the oocyte cytoplasm).This big level of Ca2+ activates anaphase-promoting complex, and meiosis II is finished.
so Iam still not sure about ovum and oocyte.

In some vertebrates meiosis II at secondary oocyte is finished before fertilization so here I will say that it is ovum.