Follicular Development

Question 1

Epithelium covering the ovaries?

Answer 1

Squamous

Question 2

Where do the vessels and nerves enter the ovaries?

Answer 2

At the hilum at one pole of the organ

Question 3

What is contained in the medulla of the ovaries?

Answer 3

Nerves
Blood vessels
Connective tissue
Stromal cells

Question 4

What is in the cortex of the ovary?

Answer 4

Germ cells in various stages of development

In immature mammals, primordial follicles - the earliest developmental stage in germ cell development.

Question 5

What does a primordial follicle consist of?

Answer 5

Oocyte

Surrounded by a layer of squamous follicular or granulosa cells

Question 6

Which hormone starts the maturation of primordial follicles at puberty?

Answer 6

FSH

Question 7

During maturation of the primordial follicle, what happens?

Answer 7

Granulosa cells become cuboidal and a single layer of them surrounds each oocyte - ‘unilaminar primary follicle’
Granulosa cells divide and become stratified - ‘multilaminar primary follicle’

Question 8

Where does the zona pellucida develop?

Answer 8

Between the granulosa cells and the oocyte

Question 9

What does the zona pellucida contain?

Answer 9

Glycoproteins

Question 10

What do the ovarian stromal cells in the outer margin of the follicle differentiate into?

Answer 10

Theca folliculi which will later secrete steroid hormones.

Question 11

What marks the formation of the secondary follicle?

Answer 11

Development of fluid-filled spaces between the granulosa cells
Theca folliculi differentiate into the theca externa and theca interna

Question 12

What do the theca interna and externa do?

Answer 12

Interna - secretes progesterone

Externa - mainly formed of vascular connective tissue

Question 13

What marks a ternary follicle?

Answer 13

Merging of the fluid-filled spaces to form a single antrum.

Oocyte surrounded by a few layers of granulosa cells known as the corona radiata

Question 14

What happens as the antrum enlarges?

Answer 14

Oocyte is pushed to one side of the follicle where is will sit on a peg of granulosa cells called the cumulus oophorus

Question 15

What happens in the final stage of development to produce the Graafian follicle?

Answer 15

Single large fluid-filled antrum
Cumulus oophorus starts to break down and the oocyte with its surrounding granulosa cells floats free in the follicular fluid

Question 16

How does ovulation occur?

Answer 16

Tissue surrounding the mature follicle becomes ischaemic and thins. Follicle ruptures and the oocyte released into the Fallopian tube.

Question 17

When are the first and second meiotic divisions completed?

Answer 17

First - when the secondary follicle is produced

Second - after fertilisation

Question 18

The theca interna secretes oestrogen - what effect does this have on other hormones?

Answer 18

Inhibits FSH which was there to develop the primordial follicles
Increases LH which controls the final maturation of the follicle and stimulates ovulation

Question 19

What secretes progesterone?

Answer 19

Granulosa cells are transformed into granulosa lutein cells by LH and they secrete progesterone.

Question 20

What is the effect of progesterone?

Answer 20

Prepares the uterine mucosa for implantation

Question 21

What happens to the corpus luteum if there is no fertilisation?

Answer 21

Starts to degenerate within two weeks of ovulation. Becomes fibrosed and hyalinised into a white connective tissue