Lecture 05: Female Gonad - Oogenesis (Kelleman)

Question 1

largest cell in the body

Answer 1

female gamete

Question 2

oogenesis =

Answer 2

formation of the female gamete

Question 3

spermatogenesis =

Answer 3

formation of the male gamete

Question 4

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

Answer 4

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.

Question 5

primordial germ cells migrate from where to where?

Answer 5

from yolk sac to genital ridge

Question 6

PGCs undergo mitosis or meisosis?

Answer 6

mitosis

Question 7

oogonia and how do they replicate?

Answer 7

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

Question 8

primary oocyte

Answer 8

formed by meiosis of oogonia. Still 2n diploid!

Question 9

folliculogenesis

Answer 9

formation of an antral follicle starting from a primordial follicle

Question 10

follicle =

Answer 10

oocyte surrounded by somatic cells

Question 11

difference between tertiary and Graafian follicle?

Answer 11

antrum has formed in Graafian follicle

Question 12

What does LH control? ***

Answer 12

ovulation (final follicular maturation)

Question 13

primordial follicle and when is it formed? **

Answer 13

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

Question 14

Primary follicle

Answer 14

oocyte surrounded by a single layer of cuboidal granulosa cells

Question 15

when does zona pellucida start forming?

Answer 15

in primary follicle

Question 16

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

Answer 16

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

Question 17

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

Answer 17

tertiary follicle

Question 18

FSH fx

Answer 18

stimulates follicular growth

Question 19

LH fx

Answer 19

maturation of the oocyte, triggers ovulation

Question 20

location of FSH receptors

Answer 20

granulosa cells

Question 21

location of LH receptors

Answer 21

thecal cells, (+granulosa cells in late stages)

Question 22

Two-cell-two-gonadotropin-hypothesis

Answer 22

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

Question 23

1st meiotic division

Answer 23

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

Question 24

2nd meiotic division

Answer 24

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

Question 25

synthesis phase of 1st meiotic division

Answer 25

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

Question 26

5 subphases of prophase I

Answer 26

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

Question 27

leptotene phase of prophase I

Answer 27

1st subphase. condensation of chromatin into thin threads

Question 28

zygotene phase of prophase I

Answer 28

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

Question 29

pachytene phase of prophase I

Answer 29

3rd subphase. Crossing over occurs

Question 30

diplotene phase of prophase I

Answer 30

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

Question 31

diakinesis phase of prophase I

Answer 31

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

Question 32

Metaphase I

Answer 32

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

Question 33

Anaphase I

Answer 33

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

Question 34

Telophase I

Answer 34

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

Question 35

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

Answer 35

Metaphase II. Resumes after fertilization to complete second meiotic division

Question 36

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

Answer 36

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

Question 37

when does oogonia become primary oocyte?

Answer 37

when it independently starts meiosis

Question 38

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

Answer 38

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

Question 39

cortical granules fx

Answer 39

surround oocyte to prevent polyspermy

Question 40

when does 1st meiotic division end?

Answer 40

when 1st polar body is extruded

Question 41

when does 2nd meiotic division end?

Answer 41

upon fertilization and extrusion of 2nd polar body

Question 42

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

Answer 42

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

Question 43

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

Answer 43

:)