Are primary oocytes arrested in the S phase or G1/G0 phase from birth to puberty?

[stester77s]

I am getting conflicting answers from different sources. I think this highlights some misunderstanding.

We start with a single oogonium (diploid) that undergoes mitosis to produce a primary oocyte (diploid). Then does that primary oocyte stay arrested in G1? Or does it replicate, go through S phase, and then stay arrested in S phase? Diagrams show conflicting answers.


Please answer this as well: When and where does the primary oocyte begin divide into the secondary oocyte and polar bodies? Does this occur in the ovary or in the fallopian tube?

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[premed1001]

nevermind

 

[FCMike11]

Whatd you figure out? I believe is it in G1 phase until a female begins ovulation.

 

[premed1001]

The first arrest isin prophase 1 and second arrest is in metaphase 2

Not sure which g phase these are in, I don't think they are in a g phase?

 

[DrknoSDN]

Those are M phase. Mitosis.
Between G2 and the next G1.

Primary Oocyte arrested at Prophase 1
2nd-ary Oocyte arrested at Metaphase 2 (metaphase is 2nd phase of Mitosis makes it easy to remember.)

 

[30somethingyearold]

Those are M phase. Mitosis.
Between G2 and the next G1.

Primary Oocyte arrested at Prophase 1
2nd-ary Oocyte arrested at Metaphase 2 (metaphase is 2nd phase of Mitosis makes it easy to remember.)

@DrknoSDN: don't you mean in Meiosis not mitosis?
Primary oocyte will arrest in prophase I, meiosis I
2nd-ary oocyte will arrest in metaphase II, meiosis, II

 

[30somethingyearold]

Found this easy way to remember from a blog:
"Basically, you can think of oogenesis as one big arrested development (like the TV show!), with lazy primary and secondary oocytes napping whenever they can. But how to remember when each will take a nap? Easy -- number 1 and number 2!
Number 1: The PRIMARY oocyte will arrest in the FIRST phase (prophase) of meiosis I.
Number 2: SECONDARY oocyte will arrest in the SECOND phase (metaphase) of meiosis II.."

All in M phase as DrknoSDN mentioned.

I'm not sure about your 2nd question: When and where does the primary oocyte begin divide into the secondary oocyte and polar bodies? Does this occur in the ovary or in the fallopian tube?
I think in the fallopian tube....anyone know the answer to this?

 

[DrknoSDN]

@DrknoSDN: don't you mean in Meiosis not mitosis?
Primary oocyte will arrest in prophase I, meiosis I
2nd-ary oocyte will arrest in metaphase II, meiosis, II

Yes, Sorry I actually thought about rewording it when I was typing. I looked online and M phase is usually in reference to Mitosis and cell cycle.
Was trying generalize that metaphase is the 2nd stage of all mitotic divisions (M phase) because that was his previous question.
But yeah Oocytes arrest at Prophase Meiosis 1 and Metaphase Meiosis 2. =)

 

[syoung]

Found this easy way to remember from a blog:
"Basically, you can think of oogenesis as one big arrested development (like the TV show!), with lazy primary and secondary oocytes napping whenever they can. But how to remember when each will take a nap? Easy -- number 1 and number 2!
Number 1: The PRIMARY oocyte will arrest in the FIRST phase (prophase) of meiosis I.
Number 2: SECONDARY oocyte will arrest in the SECOND phase (metaphase) of meiosis II.."

All in M phase as DrknoSDN mentioned.

I'm not sure about your 2nd question: When and where does the primary oocyte begin divide into the secondary oocyte and polar bodies? Does this occur in the ovary or in the fallopian tube?
I think in the fallopian tube....anyone know the answer to this?

I would hazard ovary.

 

[NonTradJp]

I've been wondering about the meiotic arrest since I first took general biology! I asked my professors and I got conflicting answer too. Thank you for the memory device.

May i ask a related question: how do the cells survive if their chromosomes are locked in this tightly packed form. Won't they degrade all their proteins and apoptosed? Only have undergrad gen bio/genetics/dev bio

 

[sillyjoe]

Those are M phase. Mitosis.
Between G2 and the next G1.

Primary Oocyte arrested at Prophase 1
2nd-ary Oocyte arrested at Metaphase 2 (metaphase is 2nd phase of Mitosis makes it easy to remember.)

Always on the money @DrknoSDN