At what stage is the developing oocyte when it is expelled from the ovary?

[FROGGBUSTER]

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We have arrest of the primary oocyte in Prophase of Meiosis I from birth until the onset of puberty, and then we have arrest of the secondary oocyte in Metaphase of Meiosis II when it gets swept into the oviduct.

But what stage is it at when it is expelled from the ovary?

edit: Found the answer, but I have a new question in the next post!!!

Immediately prior to ovulation the developing primary oocyte completes meiosis I and is then released from the ovaries. The developing ovum, now referred to as a secondary oocyte, quickly initiates meiosis II, but arrests once again in metaphase. Penetration of a sperm at fertilization, which usually occurs in a fallopian tube, induces the secondary oocyte to resume and complete meiosis II.

 

[FROGGBUSTER]

Can you guys answer this question for me?


A developing primary oocyte typically completes meiosis I immediately prior to ovulation. After arresting in metaphase of meiosis II, the developing ovum cannot resume meiosis II until sperm penetration is initiated. Where would you be most likely to find the first polar body produced during the development of an ovum?

A. Ovary.
B. Body cavity.
C. Ampulla of fallopian tube.
D. Uterus.
E. Cervix.

The answer is "uterus" but that doesn't make sense to me if Meiosis I is completed before expulsion of the secondary oocyte...

 

[HannibalLecter]

Can you guys answer this question for me?


A developing primary oocyte typically completes meiosis I immediately prior to ovulation. After arresting in metaphase of meiosis II, the developing ovum cannot resume meiosis II until sperm penetration is initiated. Where would you be most likely to find the first polar body produced during the development of an ovum?

A. Ovary.
B. Body cavity.
C. Ampulla of fallopian tube.
D. Uterus.
E. Cervix.

The answer is "uterus" but that doesn't make sense to me if Meiosis I is completed before expulsion of the secondary oocyte...

Ok this one is actually tougher than it seems:

The polar bodies never actually leave the cell even though they are diagrammed that way in many figures you might have looked at in different txts. But in Grays anatomy: http://en.wikipedia.org/wiki/File:Gray8.png, it details that the polar bodies remain in the ovum complex even though the nuclei have separated. Its similar to endosperm forming in plants but no fertilization of the polar body occurs because in this case it goes into a lonely place of the cell and is ignored. Reminiscent of my childhood.

 

[FROGGBUSTER]

I actually knew that all 3 polar bodies are released from the ovum at the same time somewhere in the uterus, but I still don't understand why the answer to that particular question of asking where it is produced is "uterus."

The PRODUCTION of the first polar body occurs in the ovaries right? And its RELEASE from the ovum occurs in the uterus.

When the question is saying "produced," does it just actually mean "released" then? That's the only way I can see how it could be correct...

 

[HannibalLecter]

I actually knew that all 3 polar bodies are released from the ovum at the same time somewhere in the uterus, but I still don't understand why the answer to that particular question of asking where it is produced is "uterus."

The PRODUCTION of the first polar body occurs in the ovaries right? And its RELEASE from the ovum occurs in the uterus.

When the question is saying "produced," does it just actually mean "released" then? That's the only way I can see how it could be correct...

Yes the production of the first polar body occurs in the ovary in the primary follicle --> graffarian follicle stage so you are right, I saw the question worded as when the ovum was produced as in released but it could be the other way around as well when it is actually produced which would be in the ovary. So could go both ways on this one.

 

[FROGGBUSTER]

Thanks man, I appreciate it. 🙂