Fertilization & Implantation Flashcards
How does cervical mucous change in response to oestrogen?
Increases volume
Decreases viscosity (clear, watery mucous)
High threadability
Receptive to sperm - contains channels for sperm access
How does cervical mucous change in response to progesterone?
Highly viscous
Cross linked
Barrier to sperm penetration
Primordial follicle:
Following a ___ surge meiosis is resumed and the first division is completed (stops at ____)
LH
Second metaphase
Mixing of prostatic and seminal fluids in vagina -> ____ holding ejaculate together -> adheres ejaculate to female reproductive tract
Coagulum
____ occurs within 2-15 mins of ejaculation
Liquefaction
Vaginal pH is normally __ but is buffered by seminal plasma to around ___
- 7
7. 2
How do the tails of normal sperm affect cervical mucus?
Causes fibres of cervical mucus to vibrate in rhythm -> facilitate movement
A patient trying to avoid pregnancy should avoid intercourse within __ days of ovulation
5
What are the survival times of sperm:
Vagina
Cervix
Uterus
Oviduct
Vagina - 2.5h
Cervix - 48h
Uterus - 24h
Oviduct - 48h
It takes the sperm approx. ___ hours to reach the ampulla.
2-7
Where does fertilisation usually occur?
In the isthmus-ampulla junction of the fallopian tubes
Sperm arriving in the uterus induces an infiltration of _____
Leucocytes
What changes occur in sperm during capacitation?
- Removal of capacitation inhibitory substances
- Loss of cholesterol from membrane
- Sperm hyperactivation
What is contained in the acrosome?
Proteinases and other enzymes
What are the two known triggers of the acrosome reaction?
Progesterone and ZP3
_____ secreted from the acrosome digests the basement membrane to assist sperm squeezing between cumulus cells
Hylauronidase
Enzymes of acrosome assist sperm penetration through the Zona pellucida to the _____ space
Perivitelline
Entry of a sperm into the oocyte triggers a release of intracellular ____
Calcium
_____ are released into the perivitelline space in the cortical reaction
Cortical granules
Release of cortical granules causes ____ of the zona pellucida
Cross-linking
How does Ca influx post fertilisation cause meiosis resumption?
- Destabilises a protein complex holding chromosomes together in metaphase
- Chromosomes migrate to poles for meiosis to resume
The zygote ~___ days to traverse the tube and enter the uterus
5
The embryo is called the morula at the ___ cell stage
16
The embryo is called the blastocyst at the ___ cell stage
60
Trophodecterm eventually forms the _____ whereas the inner cell mass forms the ____ and ____
Trophoblast (of the placenta)
Body of foetus proper + extra embryonic structures that aren’t trophoblast derived
What is nidation?
The process by which the embryo burrows into the endometrium of the uterus.
The embryo always attaches to the dedicudalendometrial epithelium via the _____
Polar trophectoderm
