Oogenesis and spermatogenesis

Question 1

How long does oogenesis take to complete?

Answer 1

Years

Question 2

When does oogenesis begin?

Answer 2

In utero then suspended until puberty

Question 3

When does oogenesis stop?

Answer 3

Menopause

Question 4

How is oogenesis completed?

Answer 4

Fertilization

Question 5

What is a primordial germ cell?

Answer 5

The earliest mitotic precursor of gametes

Question 6

Where do primordial germ cells migrate?

Answer 6

Genital ridge

Question 7

What are oogonia?

Answer 7

The mitotic precursor of oocytes

Question 8

What are oocytes?

Answer 8

Female germ cells capable of meiosis

Question 9

What are primary and secondary oocytes?

Answer 9

Primary - first meiotic division

Secondary - seconda meiotic division

Question 10

What is a polar body?

Answer 10

Small cellular structures containing minimal cytoplasm

Question 11

What does the presence of two polar bodies indicate?

Answer 11

Fertilization (completion of second meiotic division)

Question 12

What happens to germ cell numbers during birth and development?

Answer 12

They massively decline due to the limited number of mitotic divisions they are capable of

Question 13

How long does the ovulation cycle last?

Answer 13

Roughly 28 days

Question 14

What are the two phases of the ovulation cycle?

Answer 14

Follicular phase

Luteal phase

Question 15

What is the follicular phase?

Answer 15

Maturation of the egg

Ovulation

Question 16

What signals the end of the follicular phase?

Answer 16

Ovulation

Question 17

What is the luteal phase?

Answer 17

Development of corpus luteum & preparation of the reductive tract for pregnancy

Question 18

What is a primary follicle?

Answer 18

A single layer of granulosa cells which surrounds an oocyte

Question 19

How many ovum does each primary follicle produce?

Answer 19

One

Question 20

When do primary follicles degenerate to scar tissue?

Answer 20

Before the onset of puberty

Question 21

What is a secondary follicle?

Answer 21

The expanded, differentiated follicle with grows around an ovum under hormonal influence

Question 22

Which hormone is secreted in the follicular phase?

Answer 22

Oestrogen

Question 23

What is lutenisation?

Answer 23

Transformation of follicular cells into corpus luteum

Question 24

What is secreted in the luteal phase and by what?

Answer 24

Progesterone by the corpus luteum

Question 25

What signals the end of the luteal phase?

Answer 25

Degeneration of the corpus luteum (i.e menstruation)

Question 26

What happens to the corpus luteum if fetilisation occurs?

Answer 26

It persists and produces increasing quantities of oestrogen and progesterone

Question 27

What is the extra-ovarian hormonal axis?

Answer 27

Hypothalamus secretes GnRH | Anterior pituitary secretes FSH and LH in response

Question 28

What do FSH and LH act on in females respectively?

Answer 28

Ovaries

Question 29

What effect does FSH have on a female?

Answer 29

Stimulates follicular development

Question 30

What effect does LH have on a female?

Answer 30

Stimulates follicular maturation, ovulation and corpus luteum development

Question 31

What combined effect do FSH and LH have on a female?

Answer 31

Secretion of oestradiol and ovulation

Question 32

How does the extra-ovarian hormonal axis work during the follicular phase?

Answer 32

Hypothalamus secretes GnRH Anterior pituitary secretes much FSH and little LH FSH causes the granulosa and theca cells of a dozen follicles to develop

Question 33

What do theca cells do?

Answer 33

Produce androgen

Question 34

What do the granulosa cells do?

Answer 34

Convert androgen to oestradiol by secreted aromatase

Question 35

What effect does oestradiol have?

Answer 35

Thickens endometrium and thins cervical mucus | Supresses FSH production by the anterior pituitary

Question 36

What does the granulosa of the dominant follicle express?

Answer 36

LH receptors

Question 37

What do high oestrogen levels mid cycle cause?

Answer 37

Hypothalamic release of GnRH in turn causing a surge of FSH and LH to be released from the anterior pituitary

Question 38

What happens during ovulation?

Answer 38

Increased follicular fluid and granulosa Cumulus oophorus loosens Follicular wall weakens Cumulus-oocyte complex (COC) picked up by oviduct

Question 39

What stimulates ovulation?

Answer 39

Surge of FSH and LH

Question 40

What happens to hormone levels after ovulation?

Answer 40

FSH and LH fall

Question 41

How do we test for ovulation?

Answer 41

LH levels in urine (high --> low) Increased temperature High progesterone levels

Question 42

What happens if there is no hCG production from an embyro 12 days after ovulation?

Answer 42

Corpus luteum degenerates to corpus albicans

Question 43

What is hCG and what is it secreted by?

Answer 43

Human corionic gonadotrophin. Implanted embryos

Question 44

What happens to progesterone and oestrogen levels if there is no fertilisation in the luteal phase?

Answer 44

They fall

Question 45

What function does hCG have?

Answer 45

Maintains corpus luteum

Question 46

What does progesterone do to ovulation?

Answer 46

Suppresses it

Question 47

What happens around 6 weeks after fertilisation to the corpus luteum?

Answer 47

It degenerates to corpus albicans as the placenta takes over its role

Question 48

When is surgical sperm aspiration indicated?

Answer 48

Azoospermia

Question 49

Which hormones stimulate spermatogenesis?

Answer 49

FSH | Testosterone

Question 50

Which hormones decrease the secretion of FSH in men?

Answer 50

Inhibin

Question 51

What hormones decrease the secretion of GnRH and LH?

Answer 51

Testosterone

Question 52

What does LH stimulate in males?

Answer 52

Testosterone secretion