Lecture 05: Female Gonad - Oogenesis (Kelleman) Flashcards Preview

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Flashcards in Lecture 05: Female Gonad - Oogenesis (Kelleman) Deck (43)
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1
Q

largest cell in the body

A

female gamete

2
Q

oogenesis =

A

formation of the female gamete

3
Q

spermatogenesis =

A

formation of the male gamete

4
Q

When does oogenesis arrest? ** When does it resume development?

A

Prophase I (late diplotene/dictyate stage). Resumes development either by LH surge during ovulation, or by hormonal control pre-ovulation. In the latter case, it will only reach metaphase II. Ultimately, fertilization must occur for oocyte to fully develop.

5
Q

primordial germ cells migrate from where to where?

A

from yolk sac to genital ridge

6
Q

PGCs undergo mitosis or meisosis?

A

mitosis

7
Q

oogonia and how do they replicate?

A

PGCs that have reached genital ridge and lost their motility. 2n. Replicate by mitosis

8
Q

primary oocyte

A

formed by meiosis of oogonia. Still 2n diploid!

9
Q

folliculogenesis

A

formation of an antral follicle starting from a primordial follicle

10
Q

follicle =

A

oocyte surrounded by somatic cells

11
Q

difference between tertiary and Graafian follicle?

A

antrum has formed in Graafian follicle

12
Q

What does LH control? ***

A

ovulation (final follicular maturation)

13
Q

primordial follicle and when is it formed? **

A

Primary oocyte surrounded by a single layer of pregranulosa cells. Forms during fetal life

14
Q

Primary follicle

A

oocyte surrounded by a single layer of cuboidal granulosa cells

15
Q

when does zona pellucida start forming?

A

in primary follicle

16
Q

at what stage does follicle develop independent blood supply and become sensitive to hormone regulation?

A

secondary follicle (early development is independent of gonadotropic hormonal support)

17
Q

at what stage does theca differentiate into theca interna and externa?

A

tertiary follicle

18
Q

FSH fx

A

stimulates follicular growth

19
Q

LH fx

A

maturation of the oocyte, triggers ovulation

20
Q

location of FSH receptors

A

granulosa cells

21
Q

location of LH receptors

A

thecal cells, (+granulosa cells in late stages)

22
Q

Two-cell-two-gonadotropin-hypothesis

A

thecal cells produce androgens via LH, which then diffuse into granulosa cells where they are converted to estrogens via FSH

23
Q

1st meiotic division

A

separates homologous chromosomes. Results in two haploid daughter cells which each contain only 1 copy of each homolog

24
Q

2nd meiotic division

A

separates the two sister chromatids from eachother. Results in 4 haploid cells

25
Q

synthesis phase of 1st meiotic division

A

Occurs before prophase I. Results in two-chromatid chromosomes (2n, 4C), in a diploid stem cell

26
Q

5 subphases of prophase I

A

1) leptotene
2) zygotene
3) pachytene
4) diplotene
5) diakinesis

27
Q

leptotene phase of prophase I

A

1st subphase. condensation of chromatin into thin threads

28
Q

zygotene phase of prophase I

A

2nd subphase. Homologous chromosomes pair (known as synapsis)

29
Q

pachytene phase of prophase I

A

3rd subphase. Crossing over occurs

30
Q

diplotene phase of prophase I

A

4th subphase. Homologs separate. Where first meiotic arrest occurs

31
Q

diakinesis phase of prophase I

A

5th subphase. centromeres move away from each other and nuclear membrane breaks down. Occurs AFTER meiosis is resumed, after LH surge preceding ovulation

32
Q

Metaphase I

A

homologs align on metaphase plate (2n, 4C)

33
Q

Anaphase I

A

homologs are separated from eachother (2n, 4C)

34
Q

Telophase I

A

two unequal daghter cells are formed, each containing 1 copy of homologous chromosome pair. (1n, 2C)

35
Q

When does SECOND arrest of oogenesis occur? When does it resume?

A

Metaphase II. Resumes after fertilization to complete second meiotic division

36
Q

2nd meiotic division is similar to ______ but results in what kind of cells?

A

mitosis; forms polar body and pronucleate oocyte (what joins with sperm) which are both 1n, 1C

37
Q

when does oogonia become primary oocyte?

A

when it independently starts meiosis

38
Q

What happens to oocyte after 1st meiotic block/arrest?

A

oocyte dramatically increases in size, zona pellucida forms, follicle housing oocyte develops

39
Q

cortical granules fx

A

surround oocyte to prevent polyspermy

40
Q

when does 1st meiotic division end?

A

when 1st polar body is extruded

41
Q

when does 2nd meiotic division end?

A

upon fertilization and extrusion of 2nd polar body

42
Q

how many chromosomes/chromatids in primary oocyte? secondary oocyte? pronucleated egg?

A

primary: 2n,4C
secondary: 1n,2C
pronucleated egg: 1n,1C (is formed after fertilization; what joins with sperm)

43
Q

sidenote: females, like males, have the capacity to renew their germ cell pool during adult life

A

:)

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