Oogenesis

Question 1

Know the 4 phases of oocyte maturation.

Answer 1

-Primordial oocyte
-Primary oocyte
-Secondary oocyte
-Ootid

Question 2

What follicles are primary oocytes found in?

Answer 2

-Primordial follicles
-Primary follicles
-Secondary follicles
-Tertiary follicles

Question 3

What follicles are secondary oocytes found in?

Answer 3

Ovulation follicles

Question 4

Define/describe the zona pellucida

Answer 4

-A glycoprotein-rich layer surrounding the egg
-Designated Zona Protein (ZP) 1, 2, and 3: Sperm binds to ZP3

Question 5

Know what polar bodies are.

Answer 5

-A small cell produced during egg maturation
-Contains one set of chromosomes

Question 6

Know how oogenesis occurs

Answer 6

-primordial germ cell: Mitosis
-Oogonia (diploid)
-primary oocyte
-LH surge: meiotic inhibitors removed
-secondary oocyte
-ovulation
-second meiotic diision producing second polar body
-Fertilization
-ootid
-Zygote

Question 7

Primordial germ cell

Answer 7

-prenatal
- Precursor cells that give rise to eggs and sperm
-2n (diploid)
-Mitosis

Question 8

Primary oocyte

Answer 8

-prenatal and post pubertal
-4n
-Primary oocytes are present throughout follicle development: primordial, primary, secondary, and tertiary follicle (Dominant)
-Meiotic prophase begins and DNA replicates
-Nuclear arret at end of first meiotic prophase

Question 9

Secondary oocyte

Answer 9

-LH surge signals progression up to metaphase 2: Rearrested into dictyate
-Cortical granules move to just inside oocyte plasma membrane
-Perivitelline space completely formed
-First polar body discards half the DNA
-2n cell

Question 10

Ootid

Answer 10

-Post-pubertal
-An immature egg with two pronuclei that have not yet combined.
-Second polar body discards half the remaining DNA
-Contact with sperm cell
-1n Cell

Question 11

Zygote

Answer 11

-The cell formed by the fusion of the egg and sperm
-Fusion of maternal and paternal
-1n cell from each

Question 12

Know the characteristics of primordial germ cells.

Answer 12

-Found in prenatal fetus
-Originate from the gut and migrate to developing gonads
-10-20 micrometers
-Mitotic divisions: 20-100 cells divide into millions
-2n cells

Question 13

Know the characteristics of primary oocytes.

Answer 13

-Prenatal and post-pubertal
-Progression into 1st meiotic prophase
-Development pauses in prophase 1 (Dictyate: Period of prolonged rest)
-4n cells
-Primary oocytes are present throughout follicle development

Question 14

How does the primary oocyte change in a primordial follicle as it grows and develops.

Answer 14

-Single layer squamous epithelial cells
-Primordial resting pool

Question 15

How does the primary oocyte change in a primary follicle as it grows and develops.

Answer 15

-Single layer of 11-20 cuboidal granulosa cells
-Begin to see increase in organelles
-Elongated mitochondria and dividing mitochondria
-Smooth and rough ER

Question 16

How does the primary oocyte change in a secondary follicle as it grows and develops.

Answer 16

-Second layer of granulosa cells
-Initial deposition of zona pellucida: glycoproteins
-Cortical granules formed
-Oocyte begins RNA synthesis

Question 17

How does the primary oocyte change in an early tertiary follicle as it grows and develops.

Answer 17

Becomes transcriptionally active

Question 18

How does the primary oocyte change in a tertiary follicle as it grows and develops.

Answer 18

-Perivitelline space appears
-Free smooth and rough ER decrease
-Hooded mitochondria appear
-Organelles cluster and nucleus migrate to periphery: Mitochondria, Golgi bodies, and Cortical granule

Question 19

How does the primary oocyte change in a dominant follicle as it grows and develops.

Answer 19

-Increase in lipid content
-Decrease in size of Golgi bodies
-Cortical granules move closer to plasma membrane

Question 20

Describe what happens to the oocyte as a result of the LH surge.

Answer 20

-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 resumes

Question 21

Know stages at which meiosis becomes arrested and what events release each arrest.

Answer 21

-Prenatal: Meiosis is first arrested in Prophase 1
-LH surge: Continues and arrested again in Metaphase 2
-Fertilization: Completes meiosis 2