Oogenesis and spermatogenesis Flashcards Preview

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Flashcards in Oogenesis and spermatogenesis Deck (52):
1

How long does oogenesis take to complete?

Years

2

When does oogenesis begin?

In utero then suspended until puberty

3

When does oogenesis stop?

Menopause

4

How is oogenesis completed?

Fertilization

5

What is a primordial germ cell?

The earliest mitotic precursor of gametes

6

Where do primordial germ cells migrate?

Genital ridge

7

What are oogonia?

The mitotic precursor of oocytes

8

What are oocytes?

Female germ cells capable of meiosis

9

What are primary and secondary oocytes?

Primary - first meiotic division
Secondary - seconda meiotic division

10

What is a polar body?

Small cellular structures containing minimal cytoplasm

11

What does the presence of two polar bodies indicate?

Fertilization (completion of second meiotic division)

12

What happens to germ cell numbers during birth and development?

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

13

How long does the ovulation cycle last?

Roughly 28 days

14

What are the two phases of the ovulation cycle?

Follicular phase
Luteal phase

15

What is the follicular phase?

Maturation of the egg
Ovulation

16

What signals the end of the follicular phase?

Ovulation

17

What is the luteal phase?

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

18

What is a primary follicle?

A single layer of granulosa cells which surrounds an oocyte

19

How many ovum does each primary follicle produce?

One

20

When do primary follicles degenerate to scar tissue?

Before the onset of puberty

21

What is a secondary follicle?

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

22

Which hormone is secreted in the follicular phase?

Oestrogen

23

What is lutenisation?

Transformation of follicular cells into corpus luteum

24

What is secreted in the luteal phase and by what?

Progesterone by the corpus luteum

25

What signals the end of the luteal phase?

Degeneration of the corpus luteum (i.e menstruation)

26

What happens to the corpus luteum if fetilisation occurs?

It persists and produces increasing quantities of oestrogen and progesterone

27

What is the extra-ovarian hormonal axis?

Hypothalamus secretes GnRH
Anterior pituitary secretes FSH and LH in response

28

What do FSH and LH act on in females respectively?

Ovaries

29

What effect does FSH have on a female?

Stimulates follicular development

30

What effect does LH have on a female?

Stimulates follicular maturation, ovulation and corpus luteum development

31

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

Secretion of oestradiol and ovulation

32

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

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

33

What do theca cells do?

Produce androgen

34

What do the granulosa cells do?

Convert androgen to oestradiol by secreted aromatase

35

What effect does oestradiol have?

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

36

What does the granulosa of the dominant follicle express?

LH receptors

37

What do high oestrogen levels mid cycle cause?

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

38

What happens during ovulation?

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

39

What stimulates ovulation?

Surge of FSH and LH

40

What happens to hormone levels after ovulation?

FSH and LH fall

41

How do we test for ovulation?

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

42

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

Corpus luteum degenerates to corpus albicans

43

What is hCG and what is it secreted by?

Human corionic gonadotrophin. Implanted embryos

44

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

They fall

45

What function does hCG have?

Maintains corpus luteum

46

What does progesterone do to ovulation?

Suppresses it

47

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

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

48

When is surgical sperm aspiration indicated?

Azoospermia

49

Which hormones stimulate spermatogenesis?

FSH
Testosterone

50

Which hormones decrease the secretion of FSH in men?

Inhibin

51

What hormones decrease the secretion of GnRH and LH?

Testosterone

52

What does LH stimulate in males?

Testosterone secretion

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