Oogenesis and Folliculogenesis

Question 1

Process of oogenesis

Answer 1

primordial germ cell (in the yolk sac) migrate to the gonadal ridge and undergo mitosis to form oogonia

Oogonia undergo mitosis to form the primary oocyte (diploid cell)

Primary oocyte will arrest in prophase 1 of miosis 1 until puberty (arrest to protect the nucleus from damage and protect from problems during fertilization)

Once puberty happens and hypothalmus gonadal axis (FSH and LH) happens and resumes/ completes Meiosis I (release 1st polar body) and begins Meiosis 2 but is arrested in metaphase II

Arrest is lifted right before ovulation and meiosis is complete to form secondary oocyte (haploid cell)

Secondary oocyte is the one that is released when ovulation occurs (EXCEPT FEMALE DOG)

Meiosis 2 happens right before or right after fertilization occurs and the second polar body is released (has half of the chromosomes)

Question 2

The primary oocyte arrests in…

Answer 2

Prophase 1 of Meiosis 1
Arrested until puberty

Question 3

Meiosis 1 of primary oocyte is complete….

Answer 3

At the time of puberty (FSH and LH)
Once meiosis 1 complete it is now a secondary oocyte

Question 4

The _________ oocyte is released at the time of ovulation (except in the Bitch)

Answer 4

Secondary

Question 5

Meiosis 2 of the secondary oocyte is complete….

Answer 5

Right before or after fertilization

Question 6

The Secondary oocyte arrests in…

Answer 6

Metaphase II of meiosis II until ovulation

Question 7

In the secondary oocyte a band is formed around the cytoplasm and will become…

Answer 7

The zona pellucida

Question 8

Process of Folliculogenesis

Answer 8

activated primordial follicle → preovulatory size by growth and differentiation of the oocyte and its surrounding granulosa cells

Primordial follicle → primary, secondary, tertiary follicles, pre-ovulatory follicle

Question 9

Initiation of follicular growth

Answer 9

Transformation of the flattened pre-granulosa cells of the primordial into a single layer of cuboidal granulosa cells (follicular) cells
Granulosa cells and oocytes participate in the activation process
Proliferation: increase of the number of granulosa layers around the oocyte;

Question 10

Follicles contain _________ oocytes until they become preovulatory follicles

Answer 10

Primary

Preovulatory follicle will contain the secondary oocyte that is ready to be ovulated (besides the bitch)