Ovary and oogenesis

Question 1

Female gamete is called ……….., and the process of it’s production is ……………..

Answer 1

The female gamete is called ova, and the process of its production is oogenesis

Question 2

Gametes are derived from …………

Answer 2

PGCs, primordial germ cells

Question 3

The PGCs are formed in the …………….

Answer 3

Epiblast

Question 4

The PGCs are formed in the epiblast during ……………. week

Answer 4

Second week

Question 5

Formed PGCs move to …………..

Answer 5

The wall of the yolk sac

Question 6

During ……… week PGCs begin to migrate from yolk sac to the gonads and arrive at …………… week

Answer 6

During 4th week PGCs begin to migrate from yolk sac to the gonads and arrive at 5th week

Question 7

Ova are derived from ………..

Answer 7

Oogonia

Question 8

………… is the female gonad

Answer 8

The ovary

Question 9

All the oogonia to be used throughout fertile life of a female are produced before her birth. True or false

Answer 9

True

Question 10

The oogonia undergo mitotic divisions, by the end of the …………. month, are arranged in clusters at the ovarian cortex.

Answer 10

Third month

Question 11

The many rounded large cells called oogonia are contained in the …………… part of the ovary

Answer 11

The cortex

Question 12

The oogonia arranged in clusters at the ovarian cortex are surrounded by ………. epithelial cells

Answer 12

Squamous/flat

Question 13

All the oogonia in one cluster are from a single follicular cell. True or false

Answer 13

True

Question 14

The total number of oogonia in the ovary reaches its maximum by the …………. month

Answer 14

5th month

Question 15

What is the maximum number of oogonia in the ovary?

Answer 15

7 million

Question 16

All surviving primary oocytes enters prophase of meiosis I, and are individually surrounded by a layer of ………….

Answer 16

Follicular cells

Question 17

A primary oocyte, with its surrounding flat epithelial cells, is called a …………..

Answer 17

Primordial follicle

Question 18

What is the state of all primary oocytes just before birth?

Answer 18

Close to the time of birth, all primary oocytes have started prophase of meiosis I, but instead of proceeding into metaphase, they enter the diplotene stage.

Question 19

Primary oocytes remain in prophase and do not finish their 1st meiotic division before puberty is reached. True or false

Answer 19

True

Question 20

Why do primary oocytes remain in prophase and not finish their 1st meiotic division before puberty is reached?

Answer 20

Oocyte maturation inhibitor (OMI), secreted by follicular cells.

Question 21

…………. Secrete OMI

Answer 21

Follicular cells

Question 22

The total number of primary oocytes at birth is about …………..

Answer 22

700,000 to 2 million.

Question 23

During childhood most oocytes become atretic and about how many are present by the beginning of puberty?

Answer 23

400 000

Question 24

About how many of the surviving oocytes are ovulated throughout the life of a female?

Answer 24

Less than 500

Question 25

The risk of having children with chromosomal abnormalities increases with maternal age indicates that primary oocytes …………………

Answer 25

are vulnerable to damage as they age.

Question 26

Each month, 15 to 20 follicles begin to mature, passing through 3 stages namely;

Answer 26

-Primary or preantral - Secondary or antral (vesicular or Graafian) - Preovulatory.

Question 27

Preovulatory stage is about ……… hours before ovulation

Answer 27

37

Question 28

……. Is the longest stage in the development of follicles

Answer 28

Antral

Question 29

When is the second meiotic division of the secondary oocyte completed?

Answer 29

After fertilisation occurs

Question 30

Outline the stages of oogenesis

Answer 30

- With each menstrual cycle, a few primary oocytes (PO) begin to mature and one completes the first meiotic division shortly before ovulation. - The first meiotic division of a primary oocyte produces 2 unequal daughter cell, each with haploid number of chromosome. - The large cell receives most cytoplasm and is called the secondary oocyte, the small cell is called the first polar body. - The secondary oocyte enters second meiotic division - Ovulation takes place while the oocyte is in the metaphase - The secondary oocyte remains arrested in metaphase till fertilization occurs - The second meiotic division is completed only if fertilization occurs. - This results in another 2 unequal daughter cells. The smaller one becomes second polar body, while the larger one is the ovum

Question 31

What happens to the secondary oocyte if fertilisation doesn’t occur?

Answer 31

If fertilization does not occur, the secondary oocyte fails to complete the 2nd meiotic division and degenerates within 24 hours after ovulation

Question 32

What is the diameter of the Graafian follicle?

Answer 32

23 - 28mm

Question 33

The heartbeat is first detected on the ………. Week

Answer 33

6th week

Question 34

When does the gonad of an embryo start developing?

Answer 34

2nd week