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Semester 1 > Female reproductive system > Flashcards

Female reproductive system Flashcards

1
Q

Outline the progression from primordial germ cell to mature oocyte

(oogenesis)

A
  1. primordial germ cell
  2. oogonia/ primordial ova
  3. primary oocyte/ primordial follicle
  4. secondary oocyte
  5. mature oocyte
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2
Q

Describe the first step of oogenesis

1.
2.
3. primary oocyte/ primordial follicle
4. secondary oocyte
5. mature oocyte

A
  • Primordial germ cells divide repeatedly as migrate from dorsal endoderm of yolk sac, along hindgut to outer surface of ovary
  • migrate into ovarian cortex, become oogonia/primordial ova
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3
Q

Another term for oogonia

A

primordial ova

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4
Q

Describe the second step of oogenesis

  1. primordial germ cell
  3. primary oocyte
  4. secondary oocyte
  5. mature oocyte
A

Each primordial ovum collects a layer of spindle cells from ovarian stroma, forming a single layer of flattened follicular cells, called granulosa cells

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5
Q

Describe the third step of oogenesis

  1. primordial germ cell
  2. oogonia/ primordial ova
  4. secondary oocyte
  5. mature oocyte
A

Oogonia/primordial ova enlarge to form primary oocytes
The primary oocyte + granulosa cells= primordial follicle

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6
Q

How many primary oocytes are there at peak and at birth, why? and why no more after birth?

A

week 20 peak= 7 million primary oocytes
cell death occurs from this point
birth= 2 million
no primary oocytes form after birth as germ cell mitosis ceases

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7
Q

what happens with the primary oocyte between birth and puberty?

(oogenesis)

A

at birth, primary oocytes begin meiosis 1, arrested late prophase 1
primary oocytes remain dormant in ovary until puberty

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8
Q

why does meiosis 1 in primary oocyte resume at puberty?

A

meiosis 1 resumes in primary oocyte due to production of FSH and LH at puberty, just before first ovulation

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9
Q

how does primary oocyte become secondary oocyte?

A

with meiosis 1, division of cytoplasm is unequal, a large secondary oocyte and a small first polar body are formed
polar body is non functional and disintegrates

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10
Q

what happens to the secondary oocyte at first?

A

secondary oocyte begins meiosis 2 but arrests in metaphase 2

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11
Q

when does meiosis 2 of secondary oocyte complete? what happens

A

if fertilisation occurs after ovulation, meiosis 2 completes, releases mature oocyte and a small second polar body

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12
Q

what is the difference between the first and second polar bodies produced in meiosis 1 and 2 of oocytes

A

first polar body contains full set of chromosomes
in the second polar body, chromosome number is halved between mature ovum and second polar body

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13
Q

do all oocytes become mature?

A

only a small percentage become mature.

those that don’t become acretic (degenerate)

400-500 will become mature during reproductive years

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14
Q

oogenesis occurs alongside - ?

A

oocytes grow and mature alongside folliculogenesis

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15
Q

what do the granulosa cells do in the primordial follicle?

A

thought provide nourishment and secrete maturation inhibiting factor

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16
Q

how are primary oocytes recruited for folliculogenesis?

A

there is continuous recruitment of primary oocytes up to ovulation, takes 7-9 months

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17
Q

Outline the progression from primordial follicle to mature follicle

A
  1. primordial follicle
  2. primary follicle
  3. secondary follicle
  4. antral follicle
  5. mature follicle
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18
Q

how is the primordial follicle formed

A

primordial ova collects layer of spindle cells, forming flattened follicular cells- granulosa cells

primordial ova enlarges to become primary oocyte

primary oocyte + granulosa cells= primordial follicle

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19
Q

What is the second step of folliculogenesis?

  1. primordial follicle

2.

  1. secondary follicle
  2. antral follicle
  3. mature follicle
A

primordial follicle becomes primary follicle through enlargement of the ovum and growth of additional layers of granulosa cells

zona pellucida appears here too

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20
Q

how do primary follicles become secondary follicles? ie what is step 3

  1. primordial follicle
  2. primary follicle

3.

  1. antral follicle
  2. mature follicle
A

FSH and LH increase first few days of monthly cycle, ► accelerated growth 6-12 primary follicles each month

rapid proliferation of granulosa cells, so many more layers-

spindle cells collect in layers around the granulosa cells creating the theca

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21
Q

what are the 2 parts of the theca on the secondary follicle

A

theca interna: epitheliod characteristics, secretes oestrogen and progesterone

theca externa: highly vascular connective tissue capsule

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22
Q

what is step 4 of folliculogenesis

what happens after the secondary follicle has developed the theca?

  1. primordial follicle
  2. primary follicle
  3. secondary follicle

4.

  1. mature follicle
A

granulosa cells secrete follicular fluid with high oestrogen concentration

causes an antrum to appear. = antral follicle

growth is accelerated, vesicular follicles form

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23
Q

what happens once we have an antral follicle?

  1. primordial follicle
  2. primary follicle
  3. secondary follicle
  4. antral follicle

5.

A

one follicle begins to outgrow the others. once others have degenerated, this is the mature follicle

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24
Q

what happens to the remainder of the follicles when one becomes the mature follicle, why

A

remainder involute in atresia (degenerate)

likely due to positive feedback loop

usually prevents more than 1 child per pregnancy

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25
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

primordial follicle

-only primary oocyte and single layer granulosa cells

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26
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

primary follicle

-more layers of granulosa cells but no theca or antrum

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27
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

antral follicle

  • has an antrum but not very big yet
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28
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

mature follicle

has big antrum and theca

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29
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

primordial follicle

only a thin layer of granulosa cells and oocyte

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30
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

primary follicle

-more granulosa cells, zona pellucida

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31
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

secondary follicle

-theca has developed, no antrum yet

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32
Q

what type of follicle cell is this and why?

(folliculogenesis)

A

mature oocyte

  • large antrum
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33
Q

talk me through this image

A

sweet

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34
Q

basic definition of menstrual cycle?

A

mestrual cycle= the regular changes in activity of ovaries and endometrium that make reproduction possible, occurs monthly

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35
Q

what does the menstrual cycle consist of

A

2 interconnected and synchronised processes, ovarian cycle and uterine/endometrial cycle

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36
Q

purpose of ovarian cycle

A

development of follicles and ovulation

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37
Q

purpose of uterine/endometrial cycle

A

thickening and shedding of endometrium

38
Q

what are the pre-ovulatory phases

A

ovarian cycle: follicular phase

uterine cycle: menstrual and proliferative phases

39
Q

what are the post ovulatory phases of the menstrual cycle

A

ovarian cycle: luteal phase

uterine: secetory phase

40
Q

which cycle and phase is the follicular phase

A

ovarian cycle, pre ovulatory

41
Q

which cycle and phase is the luteal phase

A

ovarian cycle, post ovulatory

42
Q

which cycle and phase is the menstural phase

A

uterine/endometrial, pre ovulatory

occurs first

43
Q

which cycle and phase is the proliferative phase

A

uterine/endometrial, pre ovulatory

occurs after menstrual phase

44
Q

which cycle and phase is the secretory phase

A

uterine/endometrial, post ovulatory

45
Q

fill in the blanks

A
46
Q

when does menarche occur

A

11-15

47
Q

explain the time periods of the menstrual cycle

A

onset at menarche, age 11-15

occurs monthly, only pauses for pregnancy

stops at menopause age 50

48
Q

avg length menstrual cycle

A

28 days

49
Q

what is day 1 of the menstrual cycle

A

day 1 is the first day on menstruation

50
Q

on what day does ovulation occur

A

14 days before first day of menstruation

in avg 28 day cycle this is day 14

51
Q
A
52
Q

GnRH

A

GnRH= Gonadotrophin releasing hormone

secreted in pulses by hypothalamus

pulses vary in frequency and magnitude

cause anterior pituitary to release FSH and LH in pulsatile fashion according to freq/mag

53
Q

what hormones do LH and FSH stimulate in menstrual cycle?

A

FSH and LH stimulate oestrogen and inhibin

54
Q

what do oestrogen and inhibin do in the menstrual cycle?

A

inhibit GnRH production and therefore LH and FSH

55
Q

what does FSH do in menstrual cycle?

A

stimulate follicular development

56
Q

what does LH do in menstrual cycle?

A

LH causes Graafian follicle to become corpus luteum which then produces progesterone

57
Q

what does progesterone do in the menstrual cycle

A

stimulate endometirum more receptive to implantation of fertilised ovum

58
Q

negative feedback cycle LH, FSH, oestrogen, inhibin

A

increased oestrogen, inhibin, progesterone have negative feedback effect on hypothalamus, causes decreased GnRH, so less LH and FSH, leads to less oestrogen and inhibin

59
Q

identify the theca cells and granulosa cells on this secondary follicle.

which receptors do they have

A

theca cells have LH receptors

granulosa cells have FSH receptors

60
Q

what is the first thing that happens in follicular phase?

A

theca cells develop LH receptors

granulosa cells develop FSH receptors

GnRH pulses increase, causing FSH levels to rise, stimulates 6-12 follicles to mature at accelerated rate

61
Q

what do the theca and granulosa cells do in response to FSH and LH

follicular phase

A

LH causes theca cells to produce androstendione

FSH causes granulosa cells to produce aromatase

aromatase converts androstendione to oestrogen

granulosa cells then also develop LH receptors

62
Q

what happens once the theca and granulosa cells are producing oestrogen

follicular phase

A

as follicles grow, more and more oestrogen is produced

this has negative feedback effect on hypothalamus, so less GnRH, less FSH and less FH

63
Q

what does the reduction in FSH and LH mean

follicular phase

A

with less FSH some developing folicles degenerate

follicle with the most FSH receptors continues to grow, becomes the most dominant follicle, the Graafian follicle

64
Q

what happens once we have a graafian follicle

follicular phase

A

graafian follicle secretes increasing amounts of oestrogen, surpasses a threshold level

this causes an LH surge and a lesser FSH surge

causes rapid swelling of graafian follicle

65
Q

what happens after the LH surge

follicular phase

A

ovulation!

high LH causes membrane of graafian follicle to thin, alongside increased follicular pressure

causes a stigma to form which expands, ruptures and expells the secondary oocyte

66
Q

what happens to the oocyte once LH surges

follicular phase

A

primary oocyte completes meiosis 1, secondary oocyte is expelled and guided to fallopian tube by fimbriae

ie, ovulation

67
Q

what does the uterine cycle do

A

prepare the endometrium for implantation and maintenance of pregnancy

68
Q

what is the endometrium and its parts

A

endometrium is the inner lining of the uterus, has 2 layers:

functional layer- grows thicker in response to oestrogen, sheds in menstruation

basal layer- forms foundation from which functional layer develops

69
Q

what does the degeneration of the corpus luteum (from luteal phase of previous cycle) result in

menstrual phase

A

degeneration of corpus luteum results in decreased progesterone production

70
Q

what does decreased progesterone trigger

menstrual phase

A

spiral arteries in functional endometirum contract

so blood supply lost, functional endometrium becomes ischaemis and necrotic

is shed, exits through vagina as menstruation

71
Q

what occurs in the proliferative phase

uterine cycle

A

high oestrogen levels (bc of follicular phase) stimulate thickening of endometrium, growth of endometrial glands and increased vascularity- ie reemergence of spiral arteries

rising oestrogen makes cervical mucus consistency more hospitable to spem

72
Q

what happens to the follicle once the oocyte has been expelled

luteal phase

A

remnants of follicle become corpus luteum-

the theca and granulosa cells become luteinised by LH surge

73
Q

what do the luteinised theca and granulosa cells do in corpus luteum

luteal phase

A

luteinised theca cells continue secreting androstendione, luteinised granulosa cells contune aromatase, converting the androstendione to oestrogen

however, luteineisedgranulosa cells in low LH conditions increase activity of cholesterol enzyme

74
Q

what happens when luteinised granulosa cells increase activity of cholesterol enzyme

luteal phase

A

cholesterol enzyme converts cholesterol to pregnenolone, a precursor for progesterone, so more progesterone is produced

75
Q

how does progesterone become dominant over oestrogen in luteal phase

A

progesterone has negative feedback effect on HPG axis, so FSH and LH decreases, so less oestrogen

luteinised granulosa cells secrete inhibin, further inhibiting FSH and so oestrogen production

so progesterone is dominant

76
Q

what marker is there that progesterone is dominant

A

progesterone increases basal temp

77
Q

what happens to the corpus luteum as FSH and LH levels fall, what does this cause

luteal phase

A

corpus luteum degenerates into non functional corpus albicans

causes loss of progesterone production, triggers menstruation

78
Q

what happens differently post ovulation in ovarian cycle in ovum is fertilised

A

fertilised ovum produces hCG which has similar function to LH

this prevents degeneration of corpus luteum so there is continued production of progesterone, preventing menstruation

placenta eventually takes over role of corpus luteum

79
Q

what happens in secretory phase of uterine cycle

A

high levels of progesterone from corpus luteum drives more secretions from endometrial glands that make uterus more welcoming for implantation

further thickening of endometrium and myometrium

reduction of motility of myometrium

thick acidic cervical mucus production to prevent polyspermy

80
Q

summarise the follicular phase of ovarian cycle

A
  1. GnRH increases so FSH and LH increase
  2. LH= theca cells produce androstendione and FSH= granulosa cells produce aromatase which converts androstendione to oestrogen
  3. oestrogen negative feedback on GnRH, LH, FSH, only follicle with most FSH receptors becomes dominant, rest degenerate
  4. graafian follicle secretes lots of oestrogen, triggers LH surge
  5. LH surge raises pressure of and thins membrane of follicle, oocyte expelled
81
Q

summarise the luteal phase of the ovarian cycle

A
  1. remnants of follicle become corpus luteum
  2. luteinised theca and granulosa cells continue producing oestrogen with androstendione and aromatase
  3. granulosa cells in low LH increase activity of cholesterol enzyme
  4. this converts cholesterol to pregnenelone, a precursor for progesterone
  5. progesterone levels rise, has negative feedback on HPG axis so less gnrh, fsh, lh, oestrogen, progesterone is dominant
  6. fsh and lh levels fall, corpus luteum degenerates into corpus albicans, loss of progesterone, triggers mensturation
82
Q

summarise the menstrual phase of uterine cycle

A
  1. degeneration of corpus luetum causes decreased progesterone
  2. causes spiral arteries in function endometrium to contract
  3. becomes ischaemic and necrotic
  4. sloughs off, exits through vagina
83
Q

summarise the proliferative phase of uterine cycle

A
  1. high oestrogen levels from graafian follicle stimulate thickening of endometrium, growth of endometrial galnds, increased vascularity as spiral artieries reemerge
  2. oestrogen changes cervical mucus consistency so more hospitable to sperm
84
Q

summarise secretory phase of uterine cycle

A
  1. progesterone from corpus luteum means gands secrete substances that make uterus more welcoming for implantation but thick acidic mucus production to prevent polyspermy

further thickening of endometrium/myomtrium

85
Q

GnRH

A

gonadotrophin releasing hormone

released steadily until puberty, then in pulses

releases FSH and LH from anterior pituitary

frequency and mag of pulses determine how much

86
Q

FSH

A

follicle stimulating hormone

stimulates follicular dev

causes granulosa cells to produce aromatase (converts ondrostendione to oestrogen)

therefore increased fsh goes to increased oestrogen

87
Q

LH

A

luteinising hormone

LH causes theca cells to produce androstendione, converted by aromatase to oestrogen

LH surge thins follicle mebrane, leads to ovulation

luteinised granulosa cells in low LH cause more progesterone

88
Q

oestrogen re follicles

A

androstendione from theca cells converted by aromatase from granulosa cells into oestrogen

has negative feedback on hypothalamus, so less GnRH, less FSH and LH so less oestrogen

rising oestrogen causes LH surge and so ovulation

89
Q

oestrogen re endometrium

A

stimulates thickening and vascularity of endometrium

makes cervical mucus more hospitable to sperm, optimises fertilisation

90
Q

progesterone re menstrual cycle

A

more prog= less oestrogen as negative feedback on HPG axis (gnrh to fsh and lh to oestrogen)

made by luteinised granulosa cells in low LH- chol enzyme turns chol to pregnenelone to prog

increases basal temp

91
Q

progesterone re endometrium

A

makes endometrium more receptive to implantation

thickens endometrium and myometrium

degeneration of corpus luteum= loss prog= vasoconstriction spiral arteries= sloughs off= period

Semester 1 (18 decks)

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