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Female reproductive system Flashcards

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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
what type of follicle cell is this and why? (folliculogenesis)
primordial follicle -only primary oocyte and single layer granulosa cells
26
what type of follicle cell is this and why? (folliculogenesis)
primary follicle -more layers of granulosa cells but no theca or antrum
27
what type of follicle cell is this and why? (folliculogenesis)
antral follicle - has an antrum but not very big yet
28
what type of follicle cell is this and why? (folliculogenesis)
mature follicle has big antrum and theca
29
what type of follicle cell is this and why? (folliculogenesis)
primordial follicle only a thin layer of granulosa cells and oocyte
30
what type of follicle cell is this and why? (folliculogenesis)
primary follicle -more granulosa cells, zona pellucida
31
what type of follicle cell is this and why? (folliculogenesis)
secondary follicle -theca has developed, no antrum yet
32
what type of follicle cell is this and why? (folliculogenesis)
mature oocyte - large antrum
33
talk me through this image
sweet
34
basic definition of menstrual cycle?
mestrual cycle= the regular changes in activity of ovaries and endometrium that make reproduction possible, occurs monthly
35
what does the menstrual cycle consist of
2 interconnected and synchronised processes, ovarian cycle and uterine/endometrial cycle
36
purpose of ovarian cycle
development of follicles and ovulation
37
purpose of uterine/endometrial cycle
thickening and shedding of endometrium
38
what are the pre-ovulatory phases
ovarian cycle: follicular phase uterine cycle: menstrual and proliferative phases
39
what are the post ovulatory phases of the menstrual cycle
ovarian cycle: luteal phase uterine: secetory phase
40
which cycle and phase is the follicular phase
ovarian cycle, pre ovulatory
41
which cycle and phase is the luteal phase
ovarian cycle, post ovulatory
42
which cycle and phase is the menstural phase
uterine/endometrial, pre ovulatory occurs first
43
which cycle and phase is the proliferative phase
uterine/endometrial, pre ovulatory occurs after menstrual phase
44
which cycle and phase is the secretory phase
uterine/endometrial, post ovulatory
45
fill in the blanks
46
when does menarche occur
11-15
47
explain the time periods of the menstrual cycle
onset at menarche, age 11-15 occurs monthly, only pauses for pregnancy stops at menopause age 50
48
avg length menstrual cycle
28 days
49
what is day 1 of the menstrual cycle
day 1 is the first day on menstruation
50
on what day does ovulation occur
14 days before first day of menstruation in avg 28 day cycle this is day 14
51
52
GnRH
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
what hormones do LH and FSH stimulate in menstrual cycle?
FSH and LH stimulate oestrogen and inhibin
54
what do oestrogen and inhibin do in the menstrual cycle?
inhibit GnRH production and therefore LH and FSH
55
what does FSH do in menstrual cycle?
stimulate follicular development
56
what does LH do in menstrual cycle?
LH causes Graafian follicle to become corpus luteum which then produces progesterone
57
what does progesterone do in the menstrual cycle
stimulate endometirum more receptive to implantation of fertilised ovum
58
negative feedback cycle LH, FSH, oestrogen, inhibin
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
identify the theca cells and granulosa cells on this secondary follicle. which receptors do they have
theca cells have LH receptors granulosa cells have FSH receptors
60
what is the first thing that happens in follicular phase?
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
what do the theca and granulosa cells do in response to FSH and LH follicular phase
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
what happens once the theca and granulosa cells are producing oestrogen follicular phase
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
what does the reduction in FSH and LH mean follicular phase
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
what happens once we have a graafian follicle follicular phase
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
what happens after the LH surge follicular phase
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
what happens to the oocyte once LH surges follicular phase
primary oocyte completes meiosis 1, secondary oocyte is expelled and guided to fallopian tube by fimbriae ie, ovulation
67
what does the uterine cycle do
prepare the endometrium for implantation and maintenance of pregnancy
68
what is the endometrium and its parts
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
what does the degeneration of the corpus luteum (from luteal phase of previous cycle) result in menstrual phase
degeneration of corpus luteum results in decreased progesterone production
70
what does decreased progesterone trigger menstrual phase
spiral arteries in functional endometirum contract so blood supply lost, functional endometrium becomes ischaemis and necrotic is shed, exits through vagina as menstruation
71
what occurs in the proliferative phase uterine cycle
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
what happens to the follicle once the oocyte has been expelled luteal phase
remnants of follicle become corpus luteum- the theca and granulosa cells become luteinised by LH surge
73
what do the luteinised theca and granulosa cells do in corpus luteum luteal phase
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
what happens when luteinised granulosa cells increase activity of cholesterol enzyme luteal phase
cholesterol enzyme converts cholesterol to pregnenolone, a precursor for progesterone, so more progesterone is produced
75
how does progesterone become dominant over oestrogen in luteal phase
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
what marker is there that progesterone is dominant
progesterone increases basal temp
77
what happens to the corpus luteum as FSH and LH levels fall, what does this cause luteal phase
corpus luteum degenerates into non functional corpus albicans causes loss of progesterone production, triggers menstruation
78
what happens differently post ovulation in ovarian cycle in ovum is fertilised
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
what happens in secretory phase of uterine cycle
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
summarise the follicular phase of ovarian cycle
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
summarise the luteal phase of the ovarian cycle
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
summarise the menstrual phase of uterine cycle
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
summarise the proliferative phase of uterine cycle
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
summarise secretory phase of uterine cycle
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
GnRH
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
FSH
follicle stimulating hormone stimulates follicular dev causes granulosa cells to produce aromatase (converts ondrostendione to oestrogen) therefore increased fsh goes to increased oestrogen
87
LH
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
oestrogen re follicles
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
oestrogen re endometrium
stimulates thickening and vascularity of endometrium makes cervical mucus more hospitable to sperm, optimises fertilisation
90
progesterone re menstrual cycle
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
progesterone re endometrium
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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