REPRO - Menstrual Cycle and Physiology Flashcards
Primordial Germ Cells (PGCs) undergo many cycles of mitosis, and migrate to the genital ridge. In females they enter…
ovaries to become oogonia which are diploid egg precursors
Oogonia proliferate by mitosis then..enter meiosis and arrest..
at anaphase (meiosis I) as primary oocytes
At birth what happens to the number of primary oocytes? Why?
Massive decrease as they undergo apoptosis as errors are discarded.
Where are primary oocytes packed
the cx of ovary (outer layer)
In the foetal ovary, what are the surrounding cells that condense around the oocyte and differentiate?
These secrete what? All together this is the..
Granulosa cells, secrete an acellular layer, the basal lamina
-Together structure is the “primordial follicle”
How do follicles grow initially in follicullogenesis in puberty?
follicles grow by multiplication of granulosa cells and synthesising protein, lays down the protective Zona Pellucida layer
Once the cohort start growing in folliculogenesis, what is the second layer of cells that differentiate around the basal lamina?
The theca cells
FSH drives most of folliculogenesis. But early growth is.. in this at puberty..
FSH independent..at puberty cohort of early follicles leave the resting pool and grow continously = follicle initiation
How do the antrum (follicullar fluid filed spaces) form?
-follicle increases rapidly in diametre and granulosa cells divisions increase so gaps form in the GC’s layers (becomes fluid filled)
What are follicles with an antrum (antral follicles) AKA?
Secondary follicles
Which layer is higher vascularised and brings the circulatory influences to allow growth of the follicle?
Theca cell layer
What are the contents of follicular follicle in the antrum?
- exudate of plasma
- secretatory products of oocytes and GCs
Are pre-antral or secondary follicles visible on US next to dominant follicle?
Secondary (although pre-antral is always there, just cant see)
After follicle initiation how are some recruited?
those that can respond to FSH reach right size for recruitment into menstrual cycle (MC) when FSH is at peak
What happens to those not recruited for MC?
They are growing at a different rate/stage so die.
How many cycles does it take for a follicle to go from resting stage to ovulation?
3 cycles
In the dominant follicle the steroids produced –> “ 2 cell, 2 Gonadotrophin Theory” which means..
- LH stimulates theca cells to make androgens and progesterone
- FSH stimulates granulosa cells to make oestrogens from androgens
LH receptors are only on..
Except will appear on… just before… to enable them to make…
Theca cells
appear on…GCs just before Ovulation. to enable them to make…Progesterone
FSH receptors are only on
Granulosa cells
What effect does oestrogen have on granulosa cells and on follicles?
Multiplication and more follicle growth
What happens to the meiosis just before ovulation?
They finiish meiosis I and arrest again in metaphase II until fertilisation/death
Menstrual cycle is about 28days, when is day one?
What are the phases?
Day 1 = 1st day of bleeding
-follicullar phase and luteal phase
What happens in the follicular phase of MC? Hormone?
- growth of recruited early antral follicles
- one selected to be the dominant follicle
- oestrogen
What happens in the Luteal phase of MC? Hormone?
corpus luteum remnant of dominant follicle secretes progesterone, if no fertilisation this dies after exactly 14 days
What causes the intercycle rise in FSH?
CL dies, progesterone falls, releasing the neg. feedback
The antral follicle growth with lots of neg. feedback causes LH/FSH to decrease, what makes them rise again?
-As dominant follicle matures and oestrogen increases sooo much there is a switch to positive feedback
What does the interphase rise in FSH allow for?
Recruitment of a cohort of large enough early antral follicles to grow
What happens in the midfollicular phase of the MC, leading to one dominant follicle?
-antral follicles make lots of E2 from GCs, neg feedback causes massive FSH decrease so all follicles bar 1, die.
What 3 things does the sustained high E2 level swtich to + feedback, LH surge result in?
- final oocyte maturation
- completion of meiosis I
- ovulation and empty follicle –> CL
How does the 1 dominant follicle survive the fall in FSH? (NB: -as FSH decreases LH increases)
- dominant follicle aquires LH receptors (as the gene for this is switched on by FSH) on GCells
- DF has more FSH receptors better coupled with their downstream signalling
- can sustain growth in low levels
- has more GCs
Name 4 processes in ovulation?
- blood flow to follicle increases lots
- appearance of apex/stigma on ovary wall
- local release of proteases and inflamm. mediators
- enzymatic breakdown of protien of ovary wall
What is released in ovulation? How is it collected?
Cumulus-oocyte complex, collected by fibriae of tubes and progress down by peristalsis + cilia
When meoisis I completes with the LH surge, what happens to half the chromosomes in this division? The egg is then the..?
There is unequal division as half the chromosomes are put in a small package in the egg, “1st polar body”. Making the egg now the “secondary oocyte”
What receptors does the CL have? which 2 hormones support it?
- has LH receptors
- LH and hCG support it
Name 3 functions of the progesterone secreted by the CL?
- maintains itself
- supports oocytes journey
- prepares the endometruim
- controls u.tubes cells and alters cervix secretions
What does the CL secrete oestrodiol for?
The endometrium
7/28 or 5-6/27-32 in notes is how MC is shown. What is normal variation month to month in MC?
Should be less than 4 day variation to be normal
Rough guide to time of ovulation is..
1st day of bleeding + 14
..rise in temp
…tender breasts, abdo bloating, spotting, thin mucus
The fertile period spans how many days?
Affected by?
6days, depends on lifespan of egg (up to 24hrs) and lifespan of sperm (av. 1.5days, up to 5)
What 3 layers of the uterus’s myometrium make it a dynamic organ?
- inner circular layer
- middle spiral fibre layer
- outer longitudinal layer
What layer of the uterus do uterine fibroids develop?
Myometruim
How is the endometriums vasculature specialised?
- arteries are spiralled to increase SA
- dense capillary network
What develops in the endometrium at full receptivity (1wk post ovulation)?
-uterine glands that secrete GFs, adhesion…onto the luminal surface
In the first half of the MC, oestrogen leads to proliferation of what?
Stromal layer proliferation
In the second half of the MC, progesterone leads to what?
- maturation of endometrium
- coiling of arteries
- development of glands
What is the stromal matrix?
Small collumnar cells with glandular extensions. 2-3cm thick.
Follicular phase of MC in uterus is AKA..
-stimulated by E2 from dominant follicle..result is
- Proliferative phase
- endometrium proliferation, stromal cell division, development of ciliated surface, glands expand, neoangiogenesis.
Around day 12-14 when endometrium is >4mm, there is induction of…
progesterone receptors on the endothelium
and small muscular contractions of the mypmetrium
The luteal phase of MC is AKA..
2-3days post-ovulation is a gradual rise in.. causing
Secretatory Phase
- progesterone rise causes reduced cell division
- glands become more tortuous and distend
- glycoprotein and lipids are secreted
Why does oedema occur in the secretory phase of MC? 3 reasons
- increased vascular permeability
- arterioles coil and contract
- myometrial cells enlarge and movement is supressed
What rescues the CL?
hCG from blastocyst binding to LH receptors
What causes menstruation?
Progesterone drop -> endometrium released PGs
- PGs cause constriction of spiral arterioles
- hypoxia and necrosis
- vessels dilate, bleeding starts
What remains after menstruation? What is this covered by?
The basal lamina remains and is then covered by extension of glandular epithelium
What 3 cell types do the uterine tubes have?
- secretory cells for nutrients to embryo
- columnar ciliated epithelium to waft oocyte
- non-cilliated peg cells
At the start of MC, high oestrogen causes what in the epithelial cells lining uterine tubes?
-differentiation so secretory cells secrete/ciliated cells start wafting
What happens to mucosa around ovulation/mid MC?
-mucosa increases in height for cilila to recieve the egg
If no fertilisation, what does progesterone exposure from CL cause to the uterine tubes?
- undifferentiation of the epithelium
- decrease in height of mucosa
Name 3 examples of ways the uterine tubes can be damaged.
- infection e.g. chlamydia
- endometriosis
- surgery
- adhesions
What 3 symptoms may uterine tube obstruction/damage to epithelium cause?
- pain
- infertility
- ectopic pregnancy
What are the 2 processes to assess tubal patency?
- Laporoscopy and Dye (dye via uterine cannula through cervix, see if dye emerges from fimbria)
- Hystero Salpingo Contrast Sonography (HyCoSy) dye via vagina into uterus. US see dye progress through tube
What is the 3mm thick endocervical mucosa lined with?
- single layer of colummnar mucous cells
- many tubular mucus glands emptying viscous, alkaline mucus into lumen
How does the cervical mucus viscosity change with MC in?
-thick and sticky so sperm cant get though except when ovulating, mucus becomes thin and runny
What is the ectocervix covered with?
-nonkeratinised stratified squamous epithelium (lkke vagina)
What/how makes the mucus watery in the follicular phase of MC?
-oestrogen, causes increased vascularity of cervix, oedema, transudate moves out -> watery mucus
-Midcycle what makes the mucus runny/how?
-oestrogen increase. Mucus has glycoproteins that allign and form microscopic channels that sperm can swim up
In the luteal phase what makes the mucus viscous/how?
-progesterone –> less water content, reduced secretion, more viscousm glycoproteins now form a mesh-like barrier
Vagina is 10cm tube lined by
specialised squamous epithelium
How is vagina protected from infections?
- constantly shed and flown down layers of epithelium cells
- secretions from cervix. Transudation from vaginal epithelium as plasma leaks out capillaries in the wall
- secretions change with cycle usually acidic (anti-microbial)
What lubricates the vagina?
Bartholins glands
Before planning pregnancy: weigh, smoking, alcohol, immunisations, Hb-opathy, STI screen, manage chronic disease.. Then when want to concieve focus on:
- HIV, Hep B, STI, Hb-opathy testing
- folic acid 400mcg
- mange chronic disease and alcohol and drugs
Name 3 risks with contraception.
- pills/hormones affect CNS
- neoplastic
- coil/implants can introduce infection or allergic reaction
What is the combined OCP?
Progestogen and oestrogen aka “ethinyloestradiol” approx 30mcg. Type of progestogen used varys.
How does the high oestrogen in OCP prevent ovulation?
- neg. feedback so low LH/FSH
- low FSH so follicles dont mature
- low LH so no ovulation
How do oestrogen and progesterones action on endometrium differ e.g. in OCP?
- oestrogen causes proliferation
- progestogens cause thinning
What effect do progestogens have on mucus?
-thicker cervical mucus and less contractility of uterine tubes
What are 3 disadv of OCP?
- Progestogen –> HT
- E2 –> increased risk DVT, PE and migrane
- neoplastic
- insulin resistance, Chrons, gall stones
What type of drugs can affect metabolism or E2/progestogens in OCP..? Clue rifampicin is an e.g
- liver enzyme inducing drugs
- anti-epileptics
Progesterone only contraception includes implants, injections, IUCD, POPs e.g. Desogestrel, why is this pill so popular?
- POP so can breastfeed on this, better SE profiles than OCP
- predictable bleeding
- 12hr window if you forget to take one to work
Name 3 ways the IUCD works other than hormonal?
- spermicidal
- causes inflammatory reaction–prostoglandin secretion
- mechanical effect
If pregnancy occurs with an IUCD what are the 2 risks?
- miscarrigae
- ectopic pregnancy
Name 3 contraindications for IUCD.
- pelvic infammatory disease
- suspected pregnancy
- unexplained vag. bleeding
- uterine cavity abnormalites
Diaphragm latex caps fit across vag. must be used with spermacide, name 1 adv and 1 disadv.
- can be put in advance
- must be left in 6hrs+ after
Suction cervical plastic caps also need spermacide and 6hrs+ in, what are the adv. compared to diaphragm?
-suitable for those with poor pelvic floor muscles
-no rubber allergies
-unobtrusive..
but higher faliure rate and need a suitable cervix
Fertility awareness, most fertile period is week after ovulation, so abstain around then (most accurate is 2/3rd cycle spent abstaing), name 3 adv of this method.
- non medical, can be used in developing areas
- allowed by catholic church
- can lead to closeness between partners
What are 3 disAdvs of fertility awareness method of contraception?
- faliure rate is user dependent
- need skilled teaching
- need cooperation between partners
- limited sex can cause relationship strain
When can post-coital pills be taken after UPSI?
up to 72hrs or 120hrs (copper coil)
In what post-coital scenario is a copper coil acceptable for emergency contraception?
- up to 120hrs after
- ONEx UPSI
1.5mg Levonelle - Levonorgestral - 1.7% failure rate can be used when?
- best in first 24hrs
- not with anti TB meds, or BMI over 26
- can use many times in same cycle
EllaOne - Ulipristal Acetate - 1.2% - SPeRM - Selective Progestogen Receptor Modulator. How does it work?
- delays ovulation by 5 days
- less effective if progesterone taken in 7 days before or after use
In the luteal phase, oestrogen maintains the endometrium, what does progesterone do?
- makes endometrium become secretatory and receptive to implantation
- makes cervical mucus viscous at end of L.Phase so no more sperm enter
After 14days when the CL dies by shrinking and vasculature breakdown what is left?
Corpus Albicans
Fall in which hormone means the endometrium is no longer maintained so is shed in menses?
Progesterone when CL dies
The outer layer of the oocyte at ovulation is the Cumulus Oophorus, what is it made of? What is its function?
- made of Granulosa cell remnants
- protects egg and secretes mucus
The corona radiata around the oocyte at ovulation is a secretion of what?
Extra-Cellular Matrix esp. Hyaluronic Acid
-CR is made of 2 layers of GCells just covering egg
What is the Zona Pellucida a layer of? What is its function in relation to sperm?
- a glycoprotein layer secreted by oocyte via cytoplasmic projections at LH surge, projections withdraw
- bind sperm e.g. ZP3 adheres to proteins on sperm head
What is the Perivitelline space under the ZP?
- layer to help block multiple sperm entering (prevents polyspermy)
- by undergoing changes at fertilisation
After 3 days, a 6-8 cell embryo is known as…
a morula
After 5 days, a 100 cell embryo that has begun to differentiate is known as…
a blastocyst
What three layers does a blastocyst have?
- an inner cell mass
- a fluid filled blastocoele
- the trophoblast (will be placenta)
