Fertilisation Flashcards
(20 cards)
Where does fertilisation occur in humans?
Ampulla of fallopian tube
What binds sperm to the zona pellucida?
ZP3 glycoprotein
What is the acrosome reaction?
Enzyme that release that digests the zona pellucida
Which proteins are involved in egg binding?
Izumo1 binds to Juno on the oocyte
What blocks polyspermy?
Cortical granule reaction
What triggers the cortical reaction?
A calcium wave initiated by PLCζ
What enzyme does the sperm deliver to the oocyte?
phospholipase C zeta (ζ)
What does PLCζ activate?
IP3 pathway - Ca2+ release from the ER
What does the Ca2+ wave achieve?
Completes meiosis II and prevents polyspermy
What is syngamy?
fusion of male and female pronuclei
What does the zygote become post-syngamy?
A diploid (2n) embryo
What is capacitation?
Sperm activation in the female tract
What happens to Juno post-fertilisation?
It is shed to prevent further sperm fusion
What stage is the oocyte in before fertilisation?
Arrested in metaphase II
What is the role of microtubules during fertilisation?
Align pronuclei and facilitate syngamy
What is the zona reaction?
The zona hardens and sperm binding sites are modified
What happens to the sperm mitochondria?
They are degraded; mitochondria are maternally inherited
What is the fastest block to polyspermy?
Membrane depolarisation (not used in mammals)
Which species has a fertilisation envelope?
Sea urchins
What happens immediately after fertilisation?
Cleavage begins
