Q3 - Fertilisation Flashcards
How many sperm are originally deposited in the vagina after intercourse?
300 million
What is the environment in the vagina like for the sperm?
is very acidic, so they can not survive for long here
How many sperm pass through the cervix?
10% of the original 300 million
Why is the cervix difficult for sperm to traverse?
It is blocked by cervical mucus
What does cervical mucus do?
It filters out those sperm with abnormal flagellar waveforms and agglutinates sperm of some males (cryptic female choice)
How many sperm make it through the uterus to the isthmus?
10,000
What physiological changes happen to the sperm in the uterus? What is the name of this process?
Become hyperactivated (swim faster) and head is destabilised by removal of sterols to allow entry to the egg
This is the start of capacitation
What helps sperm move through the uterus?
Uterine contractions, possibly caused by seminal fluid
What occurs when sperm reach the isthmus?
They bind to the lining where they can be stored for several days
When are sperm released from the isthmus lining?
Ovulation
How many sperm are released from the isthmus lining?
100
At ovulation, what physiological changes occur in the sperm?
They become hyperactivated (swim faster)
Capacitation is complete
How do sperm find there way to the released egg?
They are attracted to the products of ovulation
How many sperm reach the egg?
A few dozen
Name the female anatomical landmarks that the sperm must pass through in the correct order
Vagina > cervix > uterus > isthmus > oviduct
