Lecture 2: Gametogenesis II Flashcards

1
Q

In what stage of meiosis are primary oocytes arrested between birth and puberty?

A

Diplotene stage of Prophase I

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2
Q

After puberty, meiosis resumes in some oocytes. During which stage of meiosis is the oocyte again arrested?

A

Metaphase II

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3
Q

Describe follicular structure in the fetal period with respect to oogenesis.

A

Diploid oogonium, no follicle, 1 chromatid/chromosome

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4
Q

Describe follicular structure in the later fetal period through birth with respect to oogenesis.

A

Diploid primary oocyte, primodrial follicle with a few flattened follicle cells; 2 chromatids/chormosome

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5
Q

Describe follicular structure during birth through puberty with respect to oogenesis.

A

Diplid primary oocyte, primary follicle with single layer of couboidal follicle cells; ZP separates primary oocyte from follicular cells; 2 chormatids/chromosome

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6
Q

Describe follicular structrue after puberty with respect to oogenesis.

A

Diploid primary oocyte, secondary follicle with mutliple layers of follicle cells and antrum formation beginning; 2 chromatids/chromosome.

Contains haploid secondary oocyte and polar body; later follicle becomes tertiary with follicle cells, corona radiata, antrum

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7
Q

Describe follicular structure during ovulation with respect to oogenesis

A

Haploid secondary oocyte with corona radiata, thecal cells and haploid polar body; 2 chromatids/chromosome

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8
Q

Describe follicular structure during ovulation with respect to oogenesis

A

Completion of second meiotic division; fertilized ovum + second polar body; 1 chromatid/chromosome

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9
Q

List the components of the mature Graafian follicle from external to internal.

A

Theca externa, theca interna, membrana granulosa, mural granulosa cells, antrum, cumulus oophorus, zona pellucida, oocyte

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10
Q

Explain how LH receptors are formed on granulosa cells

A

FSH receptors synthesize aromatase in response to FSH, aromatase converts testosterone into estradiol, estradiol stimulates formation of LH receptors

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11
Q

What factors lead to meiotic arrest at diplotene stage of meiosis?

A

High [cAMP] which inactivates MPF (maturation promoting factor); cGMP from follicular cells inactivate phosphodiesterase 3A (maintains high [cAMP])

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12
Q

What is the role of LH in ovulation?

A

Sudden spike in LH activates adenyl cyclase, stimulating progesterone secretion and releasing oocyte/corona radiata

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13
Q

What is the fate of the follicle after ovulation occurs?

A

2nd meiotic division completed, contains fertilized ovum and polar body

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