Repro - Female physiology and fertilisation Flashcards
Where in the fallopian tube is the egg fertilised?
The Ampulla
What are the 3 layers of the uterus called?
Perimetrium
Myometrium
Endometrium
Which layer of the ovary contains the ovarian follicles (1 oocyte surrounded by 1 layer of cells)
The Cortex (peripheral part) - contains the primordial follicle pool which makes up the egg resevere of the ovary.
Which layer of the ovary contains blood vessels which supply the ovary?
The Medulla (central part)
Name 2 functions of the ovaries
- Oocyte production (1 mature egg generated per menstrual cycle)
- Steroid hormone production (estrogen, progesterone, testosterone)
50% of the testosterone in the female body is produced by the ovaries before menopause
a. true
b. false
a. True
Describe the structure of a primordial follicle?
Primary oocyte (stuck in the first meiotic division) surrounded by one layer of sqaumous pre-granulosa cells
Name the 4 stages of follicular development?
- Primordial Follicles
- Primary Follicle
- Seconday Follicle
- Tertiary/Graffian Follicle
Describe the structure of a primary follicle?
Oocyte surround by Zona Pellucida***
and 2 cell layers of CUBOIDAL granulosa cells (start to proliferate)
Describe the structure of a secondary follicle (pre antral)?
Oocyte grows in diamter
There are mutiple layers of granulosa cells
Appearance of Theca cells**
Describe the structure of a graffian (tertiary) follicle?
Follicular fluid between cells combine to form ANTRUM
first meiotoic division is complete -> secondary oocyte is formed and second meitoic division starts (pre-ovulatory)
Where are FSH and LH (gondaotrophins) released from?
The Anterior pituitary gland
Where do FSH and LH act upon in the female body?
The ovary
Which hormones do the the ovaries produce? and what organ do they act upon?
Estrogen and progesterone (steroid hormones)
Act on the uterus to co-ordinate the mentsrual cycle?
What structure releases GnRH?
The hypothalamus (gondotrophin releasing hormone)
Acts on the Anterior pituitary to release LH and FSH
Estrogen and Progesterone always exert negative feedback within the hypothalamic pituitary axis
a. True
b. False
False
Estrogen exerts positive feed during days 12-14 (mid-cycle) - increasing the production of GnRH, FSH and LH. This is to help mid cycle ovulation and is responsible for LH surge seen mid-cycle.
Describe the follicular phase of the ovarian cycle
FSH causes the follicle to mature and produce estrogen (inhibiting the development of other follicles)
- Follicles produce estrogen and increase thickness of endometrium
Describe the ovulation phase of the ovarian cycle
Follicle rupture and the secondary oocyte is released due to an LH surge
Estrogen is high and progesterone is low
Describe the luteal phase of the ovarian cycle
The ruptured follicle forms the corpus luteum and secretes progesterone and (some) estrogen
progesterone is high
Describe the menstruation phase of the ovarian cycle?
The corpus leteum degenerates and forms the corpus albicans
A new ovarian cycle can then begin.
Effect of estrogen on the endometrium?
proliferation
Estrogen is the primary regulator of endometrial proliferation.
During the proliferative phase, estrogen causes the endometrium to thicken and grow, preparing the uterus for pregnancy.
This phase can last 10–20 days, but is typically around 14 days.
Progesterone transforms the endometrium into a secretory structure
a. true
b. false
a. True
Ensures the structure is ready to recieve embryo.
Which hormone causes ovulation mid-cycle?
LH surge (due to positive feedback of estrogen on AP and hypothalamus)
What is menarche
The onset of bleeding - at puberty - 1st mentrual period
What is amenorrhoea ?
No periods!!!
can be
- primary - never had
- secondary - stopped for 6 months
What additional 2x history must be taken during a gynae history taking?
- obstetric
- sexual
Menorrhagia means?
heavy periods (HMB)
Parity means?
number of pregnancies - regardless of the outcome
Para 2 + 1
parity = number of pregnancies
= 3 pregnancies
1st number = births after 24 weeks (alive or still)
= 2 births after 24 weeks
2nd number = births, terminations, miscarriages, still births before 24 weeks
= 1
How is fundal height measured?
Palpate the fundus (top of uterus) with two hand and measure to the top of the pubic symphysis with tape.
Semi-recumbant position with empty bladder.
24 weeks = around 24 cm +/-
(is lie longitudinal, oblique, transverse)?
What is the ideal position of the foetus
Longitudinal - Cephalic
How do you know when the head is engaged and descended into the pelvis?
Only 2/5 of head is palpable abdominally
How is the sperm first able to interact with the egg during fertilisation?
The acrosome (head of sperm) reacts with the zona pellucida and periviteliine space (surrounding egg) by releasing hydrolytic enzymes
- The sperm then can react with protein receptors
- The plasma membranes of sperm and egg the fuse
- Sperm releases nucleus which enters the egg
What stops other sperm from releasing their nucleus into the egg?
Cortical granules are released which renders the vitelline layer impenetrable to other sperm
What is a morula?
ball of cells 16+
(cell division, 2, 4, 6, 8, 16+ cells on day 4 or 5)
What is a blastocyst
Forms day 5 after fertilisation
Morula develops into 2 distinct cell groups
- Trophoblasts (outer)
- Inner cell mass (endoderm)
Which layer of the blastocyst invades the maternal endometrium for plantation?
The trophoblast layer
Merge with the placenta
What are the two cell groups in the blastocyst (day 5)
- Trophoblasts
- Inner cell mass
16+-ball of cells which are undifferentiated during embyro development is called?
Merula (early embyro enters the uterine cavity in morula phase)
Which group of cells within the blastocyst give rise to the baby?
inner cell mass
outline the correct order of implantation steps
(appposition , ahdesion, hatching, invasion)
- hatching - trophoblast cells produce protease that dissolves zona and allows blastocyt to come out
- apposition - first connection between blastocyst and endometrium
- adhesion - trophoblast adheres to the epithelial layer of the maternal endometrium (hCG secreted by embryonic tissue)
- invasion - trophoblast proliferate, differentiate and cross the epithelial basement membrane/invade endometrial stroma to form the placenta.
what is appostion? in regards to implantation of the embryo
The first connection between the blastocyt (microvilli) and the endometrium (pinopodes)
pinopodes are microvilli like structures expressed on receptive endometrium.
steps of implantation (4)
- hatching - blastocyts hatches out of zona which is dissolved (trophoblast cekks secrete protease)
- apposition - attaches to pinopodes of endometrium
- adhesion - trophoblasts adhere and hCG produced
- invasion - proliferation of trophoblasts/ connection with uterine vessels
How does the embyro hatch out of the zona pellucida during the 5th day after fertilisation?
trophoblast cells secrete proteases
inability to hatch results in infertility - and premature hatching can result in abnormal implantation in the uterine tube (ectopic)
what is decidualisation
preparation of the endometrium for implantation prior to trophoblast invasion and placentation
List 3 changes to the endothelium in preparation for implantation
- stroma cell differientation (FLC fibroblast like elongated cells) -> rounded epithelial cells
- angiogenesis (+ increased vascular permeability)
- increased macrophages, lymphocytes and decidual leukocytes (uterine natural killer cells) for maternal immune tolerance
under the influence of progesterone (proliferative stage) - becoming vascular receptive tissue
The placenta is composed of tissue almost fully derived from foetal tissue
a. true
b. false
a. true
trophoblast cells (from blastocyt which has hatched)
What are the two layers of the trophoblast called?
- Cytotrophoblast (outer) - invade endometrium and remodel spiral arteries to increase blood flow
- Syncytiothrophoblast (inner)
form primary, secondary and then tertiary chorionic villi (tertiary when capillaries form)
The umbilical vein carries?
02 rich blood from the placenta TO foetus
The umbilical artery carries
02 poor blood and waste products from the foetus TO the placenta
Two layers of the trophoblast cells
- cytotrophoblast (outer)
- synctiotrophoblast (inner)
functions of the placenta
- immunological barrier
- gas exchange
- nutrient exchange
- waste excretion
- endocrine - hCG secreted
When to refer a couple for infertility investigations?
after 1 year of regular unprotected intercourse
earlier if > 35 or known cause
investigations to test for ovarian reserve
- Blood tests
- FSH on D1-D5 of cycle (<10 iu/L)
- AMH (5-0 - 25.0 pmol/L)
- USS - Antral follicilar count
approaches couples can take to see if ovulation is happening?
1.BBT - basal body temp increase (increases during ovulation and stays higher for a few days)
2. cervical muscus
3. LH ovulation kits
4. ovulation calender
clinical test for ovulation
D21(day 21) serum progesterone
only works if normal 28-30 day cycle
> 20nmol/l are satisfactory!!normal
normal sperm count
15 million/ml
how is fallopian tube patency determined ?
- HSG scan - hysterosalpingogram
(if no pelvic infection or gynaecological problem in the past)
- Laparoscopic dye test
how is uterine cavity normally investigated?
pelvic USS
medications that induce ovulation
- clomiphene citrate (oral tablets)
- gonadotrophins (direct FSH)
try lifestyle factors first
risks of IVF
- ovarian hyperstimulation syndrome
- mutiple pregnancies
the ovary ejects the oocyte into the fallopian tube in what stage of development?
secondary oocyte
in metaphase 2
attachments of cardinal ligament
cervix - lateral pelvic wall
function of bartholins gland
secretes mucus into the vestibule (area with vaginal and urethral opening) surrounded by labia minora
type of epithelium in the vagina
stratified sqaumous - deals with abraision/friction
females are born with a set amount of oogonium (diploid stem cells)
a. true
b. false
a.true
get converted to primordial follicles (frozen in prophase1)
at puberty - localised androgens stimulate primoridal follicles -> primary follicles
primary follicles have undergone mieosis 1
a. true
b. false
b. false
FSH stimulation -> start proliferating and making layers of granulosa cells
FSH stimulates proliferation of granulosa cells
a. true
b. false
a. true
FSH affects
- proliferation of granulosa cells
- formation of zona pellucida (layer of glycoprotein)
- stimulate cells to produce estrogen
cause granulosa cells to produce estrogen (androgens -> estrogen)
What do theca cells do
takes cholesterol and produces androgens
androgens then enter granulosa cells (and are converted to estrogens)
which hormone stimulates theca cells?
LH - stimulates theca cells to produce androgens (cholesterol -> androgens)
Androgens then enter granulosa cells
FSH stimulates enzymes in granulosa cells to convert androgens to estrogens
a. true
b. false
a. true
Secondary follicles are primary oocytes
a. true
b. false
a. true
hasnt finished mieosis 1
When pockets of follicular fluid coalase it is called?
ANTRUM
-> graffian follicle
primary factor stimulating follicular phase of cycle
FSH!!
(help of LH to produce androgens via theca cells)
describe the follicular phase (day 1-14 of cycle)
- mitosis of granulosa cells
- estrogen is produced
- follicular fluid is produced
what hormone rises around mid-cycle (day 14)
estrogen - exerts positive FB
tonnes of GnRH, LH
rise of LH and estrogen**
graffian follicle produce inhibin B - prevents rise of FSH
How does the LH surge act of graffian follicle
- increases permeability and blood flow to the antrum
- increased follicular fluid
- proteases activated which eat tissue around graffian follicle
- enzymes cut the structure holding egg and egg pops out of follicle
how are the fimbrie effected by the LH surge
become stiff and scrape across the surface of the ovary
this creates a fluid filled current which pushes the oocyte towards the fallopian tubes
secondary oocyte is caught when still in metaphase 2
cilia beat oocyte into the ampulla
what happens during the luteal phase
the remaining ruptured graffian follicle is converted into the corpus luteum
under influence of LH, corpus luteum is stimulated to produce progesterone (day 15-28)
what are the 3 phases of the mentsrual cycle
- menstruation - shedding of the stratum functionalis of the endometrium (day 1-5)
- proliferative (regeneration of layer) - (day 6-14 under influence of estrogen)
- secretory phase
which layer of the uterus gets shed during menstruation
stratum functionalis (has coily /spiral arteries)
arteries are branches of the uterine artery (internal iliac)
Which hormone is released after ovulation occurs and can be used as a marker of fertility?
Day 21 progesterone, also known as mid-luteal cycle progesterone, is used to test for ovulation if the woman has a regular cycle. If irregular, then you need to test progesterone a week before predicted menstruation.
Ovulation is a sign that an egg is being released, which is obviously a basic requirement for fertilisation to occur.
progesterone increases body temperature
a. true
b. false
a. true
which hormone is responsible for spiral artery development
progesterone
progesterone decreases myometrial excitability
a. true
b. false
a. true
estrogen effect on cervical mucous
stimulates uterine glands to produce thin cervical mucous
thin to prevent blocking sperm but has chemicals that help activate the sperm
which hormone is prevalent during proliferative phase of mentsrual cycle?
estrogen
- regeneration of stratum functionalis of endometrium and spiral coily arteries (angiogenesis)
- stimulates production of uterine glands**
what hormone is prevalent during the secretory phase of mentsrual cycle?
progesterone
produced by the corpus luteum
effects of progesterone on uterus
- thickens the stratum functionalis even more
- increases spiral coily arteries
- makes uterine gland start producing fluid that is rich in both glycogen, lipids and proteins
- switches to thick cervical mucous - plugs up the cervix (no access to protect the embyro
what stimulates the corpus luteum to continue producing progesterone
hCG - human gonadotrophin
stimulates corpus luteum to produce progesterone continuously
how does mentsruation occur? (days 1-5)
if no fertilisation occurs there are no signals from the embyro to the corpus luteum to produce progesterone
progesterone levels drop
spiral arteries spasm, are weak and fragile, vasoconstriction so hard - that they rupture -> blood accumulates in the stratum functionalis
-> no blood /02 to functionalis -> necrosis/tissue dies
if there are no signals from the embyro - what does the corpus luteum become?
corpus albicans
cannot produce progesterone or response to LH
what happens the corpus luteum if fertilisation occurs?
corpus luteum will produce progesterone until placenta develops in week 12
describe a primordial follicle
oocyte with 1 layer of simple squamous cells
GnRH is released at puberty
a. true
b. false
a. true
starts production of localised androgens that stimulate primordial follicles -> primary follicle -> (FSH)-> seconday follicle - (FSH) -> Graffian
what phase is day 1-14 of ovarian cycle
follicular
LH acts on theca cells to?
produce androgens
(cholesterol is converted)
FSH effect on granulosa cells
stimulates to convert androgens which enter
into estrogen
via aromatase enzyme
*estrogen is a byproduct of follicular phase
inhibin B is released by graffian follicles , what is its action?
inhibits FSH midcycle (means there is only an LH surge)
effect of LH surge
- increase in permeability of blood vessels
- triggers ovulation - proteases pop out the secondary oocyte
LH stimuates the corpus luteum to produce progesterone
a. true
b. false
a. true
Theca cells function
convert cholesterol -> androgens (androsterendre)
Granulosa cells function
Androsternede -> estrogen
via aromatase enzyme
secondary follicle (pre antral) defining feature
theca cells
how does progesterone facilitate embyro implantation?
- spiral artery development
- uterine contractions/excitability are reduced
- endometrium is maintained
- cervical mucus thickening
What receptor on the zona pellucida does the sperm bind to
ZP3 receptor
ammenorrhea
no periods
dopamine inhibits prolactin
a. true
b. false
a. true
what phase of the mentsrual cycle happens during the follicular ovarian cycle?
follicular phase is day 5-13
profilerative phase of cycle -> estrogen is produced by follicles (resulting in thickening of endometrium, formation of spiral arteries, increased vascularity and formation of glands)
what days in the cycle does ovulation occur
day 13-14
what phase of the menstrual cycle takes place during the luteal phase (day 15-28)
secretory
- corpus luteum
- endometrium changes to secretory lining under the influence of progesterone
- progesterone rises (thick cervical mucus, body temperature rises following ovulation in response to high progesterone)
- if no fertilisation - corpus luteum degenerates and progesterone falls
- estrogen will start rising again
body temperature falls prior to ovulation
a. true
b. false
a. true
and rises after when progesterone rises
What phase of development is the secondary oocyte frozen in until fertilisation?
Metaphase 2
(sits in ampulla)
