Initiation of Pregnancy Flashcards
Female fertility is episodic - what does this mean?
It must support two things:
- Support gamete transport
- Support a pregnancy
The Ovarian cycle is divided into 2 phases, what are they?
- Follicular phase
- Luteal phase
What hormones dominate in the Follicular phase?
FSH and Oestrogen
and a spike of LH at the end
What hormones dominate in the Luteal phase?
Progesterone, Oestrogen, Inhibin
How long can sperm survive in the female reproductive tract?
~ 5 days
To maximise chances of conception, what is the best day for coitus?
Day 14, assuming Day 1 is the first day of menstrual bleed
Sperm travels approx. 20cm to site of fertilisation - but how does it move?
Combination of own motility and uterine / oviduct contractions (mainly female led)
What is the “functional sperm reservoir”?
The 10-100s of sperm which have successfully migrated to the oviduct epithelia
Freshly ejaculated sperm cannot fertilise eggs - what must occur before it can successfully do so?
Capacitation must occur
Why does sperm require time away from seminal plasma / epididymal fluid before fertilising eggs?
The fluid contains (?) compounds which maintain sperm in a quiescent state
Capacitation is comprised of two stages - what are they?
Activation
Acrosome reaction
During the acrosomal reaction - two enzymes are released. What are they called and what are their roles?
Hyaluronidase: Breaks down hyaluronic acid in the cumulus
Acrosin: Breaks down the Zona Pellucida
Where does Phospholipase CZ1 come from?
Sperm cytoplasm derived
Outline the role of Phosphlipase CZ1 in Oocyte activation
- Cleaves PIP2 -> IP3
- Ca2+ levels transiently rise and fall, causing a degeneration MPF
- Eggs are arrested at MII, and is diploid, however declining MPF allows it to progress through cell cycle
- Ca also causes cortical reaction and zona pellucida hardening - prevents polyspermy
What is “polyspermy”?
An egg that has been fertilized by more than one sperm
Oocytes prior to fertilisation are arrested at what stage?
Metaphase II
What is “syngamy”?
The fusion of male and female pronuclei
At the 4 cell stage, what important genomic remodelling occurs?
DNA of embryo is removed of epigenetic markers, becomes demethylated and remethylated
What signalling occurs from the Blastocyst to the body to facilitate the continuation of a pregnancy?
- In the Luteal stage, rising Oestrogen produces a ? signal to cause a rise in local Heparin-binding EGF-like Factor
- Integrin remodelling occurs in the epithelial tract so Blastocyst can bind and become enveloped in the uterus
What two things are required specifically in the first trimester of a pregnancy?
- Leteotrophic support (LH / CL)
- hCG
Why isn’t LH or hCG required after the first trimester?
Because the foetal placental unit can synthesis enough Progesterone
Describe the relationship between hCG, LH, and the CL
- hCG binds to LH receptors on luteal cells to ensure its progesterone production
- Progesterone helps sustain the foetus
- Progesterone +feedback on luteal cells helps maintain the CL
Progesterone is synthesised from Corpus Luteum in the early stages of pregnancy - but where else can it be produced from?
The syncitiotrophoblast, from cholesterol
What are more common, monozygotic (identical) twins or dizygotic twins?
Monozygotic - 60%
Dizygotic - 40%
What are the four types of monozygotic twins?
- Dichorionic / diamniotic
- Monochorionic / diamniotic
- Monochorionic / monoamniotic
- Incomplete split -> conjoined
What % of couples after 2 years of regular unprotected sex cannot conceive?
8%
Prior to IVF, a woman must undergo a series of hormonal treatments - what are they?
- GnRH agonist: supresses FSH/LH release so several follicles grow to pre-antral stage and then arrest
- Supraphysiological doses of FSH to recruit / develop all such follicles
- LH analogue, to induce ovulation
What does ICSI stand for? What has been a recent concern of using ICSI?
Intracytoplasmic sperm injection
Low sperm count in make progeny conceived by ICSI
What is Azoospermia?
Semen which contains no sperm
For Azoospermic patients, what techniques can be used to obtain sperm?
PESA
MESA
TESA
TESE
