T3: Oocyte Maturation

Question 1

what are the 4 phases of oocyte maturation

Answer 1

1. mitotic division of primordial germ cells (early prenatal)
2. nuclear arrest (dictyotene) in prophase 1
3. cytoplasmic growth
4. resumption of meiosis following LH surge

Question 2

what are the cell types before the LH surge

Answer 2

primary oocyte

Question 3

when does the first polar body appear

Answer 3

after the LH surge

Question 4

how much genetic material in is ovulation and fertilization

Answer 4

ovulation: 2N
fertilization: 1N

Question 5

when does the second polar body appear

Answer 5

after ovulation

Question 6

what are the cell types after LH surge

Answer 6

secondary oocyte

Question 7

describe the primordial germ cells

Answer 7

-migrate to developing gonads (prenatal)
-10-20 um
-undergo mitotic divisions
-oocytes start in the gut region for farm species (they have to migrate to female gonad
-after mitotic stage= DNA synthesis
-2N

Question 8

describe the primary oocyte

Answer 8

-4N
-progress in to meiotic prophase
-arrested in prophase 1: dictyate
-Dictyate reached at 170 d post conception in cattle

Question 9

describe the primordial follicle

Answer 9

-holds the primary oocyte (arrested at dictyate)
-single layer of squamous epithelial cells
-primordial resting pool

Question 10

describe the primary follicle

Answer 10

-primary oocyte
-single layer of cuboidal granulosa cells
-increases in organelles
-elongated mitochondria and diving mitochondria
-smooth and rough ER

Question 11

describe the secondary follicle

Answer 11

-primary oocyte
-second layer of granulosa cells
-initial deposition of zona pellucida glycoproteins
-cortical granules formed
-oocyte begins RNA synthesis

Question 12

describe the zona pellucida

Answer 12

-made of glycoproteins produced by the oocyte
-zona proteins Z1,2,3
-Sperm binds to ZP3

Question 13

describe the early tertiary follicle

Answer 13

-primary oocyte
-2-3 mm
-oocyte begins to grow
-becomes transcriptionally active
-no DNA change just meiotic arrest

Question 14

describe the tertiary follicle

Answer 14

-primary oocyte
-8-9 mm
-perivitelline space appears
-oocytes stops growing at 120-130 um
-free smooth and rough ER decreases
-hooded mitochondria appear
-mitochondria, golgi bodies, cortical granule clusters and nucleus migrate to periphery

Question 15

what type of mitochondria are only found on the oocyte

Answer 15

hooded mitochondria

Question 16

describe the dominant follicle

Answer 16

-primary oocyte
-increase in lipid content
-decrease in size of golgi bodies
-cortical granules move closer to plasma membrane

Question 17

what happens during the LH surge

Answer 17

-cortical granules move to just inside the oocyte plasma membrane
-perivitelline space completely formed
-further increase in lipid content and decrease in golgi bodies
-meiosis resumed

Question 18

what is the overview of meiosis resumption

Answer 18

-primary oocyte arrested in dictyate
-with LH surge
-progresses through meiosis 1
-arrested in metaphase II
-first polar body=secondary oocyte
-oocyte ready for ovulation

Question 19

describe the overview process of the maturation

Answer 19

prenatal: primordial germ cell/mitosis(diploid)–oogonia—primary oocyte—meiotic prophase/DNA replicates—-primary oocyte still—nuclear arrest–LH SURGE (meiotic arrest lifted)

After puberty: —secondary oocyte (1 polar body)–ovulates—ootid– fertilization (2 polar bodies)—zygote