Oogenesis

Question 1

the eggs mature through an intricate coordination of _______________ (3)

Answer 1

hormones
paracrine factors
tissue anatomy

Question 2

what are the 4 stages of oogenesis

Answer 2

(1) proliferation - produce 7 million oogonia
(2) 1st meiotic division - oogonia become primary oocytes
(3) diplotene stage (dicytate resting stage)
(4.1) maturation (puberty / LH hormone surge), making it viable for sperm infusion
(4.2) resume meiosis (fertilization)

Question 3

what stage of oogenesis is this?
thousand or so PGCs reaching the developing ovary divide rapidly from the second to the seventh month of gestation - generating around 7 million oogonia

Answer 3

1st stage - proliferation

Question 4

what stage of oogenesis is this?
oogonia become primary oocytes

Answer 4

2nd stage - 1st meiotic division

Question 5

after the proliferation stage, what helps the survivor oogonia proceed to the next stage?

Answer 5

retinoic acid

Question 6

in the first meiotic division, what stage of meiosis does the oocytes remain dormant (also referred to as diplotene stage)?

Answer 6

first meiotic prophase

Question 7

what is the other term for diplotene stage?

Answer 7

dictyate resting stage

Question 8

what is the gland involved in the continuation of meiosis during puberty? what hormone does it release? what does this hormone do?

Answer 8

pituitary gland
luteneizing hormone
block and permits oocytes to resume meiotic division

Question 9

what does the LH do to the oocytes?

Answer 9

makes them mature

Question 10

after the first meiotic division, the oocytes proceed to _________

Answer 10

second meiotic metaphase

Question 11

what do oocytes do after maturing due to the LH surge?

Answer 11

oocyte begins to synthesize the proteins that make it competent to fuse with the sperm cell and that enable the first cell divisions of the early embryo

Question 12

the maturation of oocytes involve the cross-talk of ___________ between the oocyte and its _______________, both of which are maturing during this phase

Answer 12

paracrine factors
follicular cells

Question 13

what do follicle cells do?

Answer 13

activate the translation of stored oocyte mRNA encoding proteins such as the sperm-binding proteins that will be used for fertilization and the cyclins that control embryonic cell division

Question 14

upon fertilization, what ions does the egg release? what do these ions do?

Answer 14

calcium ions
release the inhibitory block and allow the haploid nucleus to form

Question 15

(oogenic meiosis)
how does oogenic meiosis and spermatogenic meiosis differ? (2)

Answer 15

(1) timing
(2) metaphase plate

Question 16

(oogenic meiosis)
what happens when the primary oocyte divides? (2)

Answer 16

(1) its nuclear envelope breaks down
(2) the metaphase spindle migrates to the periphery of the cell

Question 17

(oogenic meiosis)
explain asymmetric cytokinesis and its importance

Answer 17

Asymmetric cytokinesis: During cytokinesis (the final stage of cell division, where the cell physically splits), the cytoplasm in oogenic meiosis gets divided unevenly.

Concentrates essential materials for development in the egg cell.

Question 18

(oogenic meiosis)
what network brings the mitotic spindle to the oocyte cortex? what is it composed of? what mechanism makes this transport possible?

Answer 18

cytoskeletal network
filamentous actin
myosin-mediated contraction

Question 19

(oogenic meiosis)
at the cortex, what mediates the separation of chromosomes? what does its mutation cause?

Answer 19

oocyte specific-tubulin
infertility

Question 20

(oogenic meiosis)
at what stage of cell division produces a secondary oocyte and the first polar body?

Answer 20

telphase

Question 21

(oogenic meiosis)
at telophase, what cells are formed (2: larger and smaller cell)

Answer 21

larger: secondary oocyte
smaller: first polar body

Question 22

(oogenic meiosis)
what does the larger cell o

Question 23

(oocytes and age)

Question 24

(oocytes and age)

Question 25

often referred to as the mature egg

Answer 25

ovum

Question 26

(oocytes and age) what is the term for incorrect number of chromosomes?

Answer 26

aneuploidy

Question 27

(oocytes and age) what causes aneuploidy?

Answer 27

due primarily to errors in oocyte meiosis

Question 28

(oocytes and age) what are the 2 reasons of aneuploidy?

Answer 28

(1) breakdown of cohesin proteins: once made and assembled, cohesins remain on the chromosomes for decades, but they are gradually lost as the cell ages (2) human meiotic metaphase is remarkably long (human: 16hrs / mice: 4hrs) the linkage between the kinetochore and the spindle does not seem very stable