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19 Cards in this Set

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What is the "endpoint" of fertilization?
When the zygote attains full capacity for development and inheritance.
What is the perivitelline space?
The space between the oocyte itself and the zona pellucida. Sperm is injected here.
When is the 2nd polar body ejected?
Upon fertilization. Meiosis II must be complete.
Where are the polar bodies ejected into?
The perivitelline space.
What occurs in the epididymis?

How long are sperm in epididymis?
Sperm maturation. Acquires proteins and motility.

80-90 days
What is capacitation?
Sperm changes that occur INSIDE female repro. tract (endocervix --> tubes) that prepare egg for fertilization.

Loss of cholesterol from sperm plasma membrane. Surface charges change. Hyperactivated motility (different swimming patterns in response to different environmental conditions)
What sperm enzymes are involved in capacitation?

What is the pathway?
adenylyl cyclase and PKA.

1) Adenylyl cyclase catalyzes ATP to cAMP concentration
2) cAMP activates PKA
3) Activated PKA phosphorylates sperm proteins
How does the sperm move in the fallopian tube?
1) Binds to microtubules in oviduct.
2) Hyperactivated sperm can break away from microtubules.

THIS IS WHY HYPERACTIVATION DURING CAPACITATION IS IMPORTANT!
What are the first cells that sperm must pass through to get to egg?
Cumulous cells. Use HA to degrade cells. May be a "group effort" by sperm to break down this layer
What happens when sperm binds to ZP?
Acrosomal exocytosis. The first membrane will degrade, releasing new sets of digestive proteins.
How does acrosomal exocytosis occur? Think ZP3, Ca2+, and pH.
ZP3 binds a sperm surface receptor, which cause a transient rise in Ca2+ levels.

Increased Ca2+ levels and subsequent pH changes lead to sustained Ca2+ elevation, leading to acrosomal exocytosis.
What are Izumo and CD9?
Izumo is a sperm surface component. REQUIRED for sperm-egg binding and fusion.

CD9 is egg surface component. Knock-outs show no sperm-egg fusion.
What is egg activation?
A calcium-mediated event (CALCIUM-MEDIATED EGG ACTIVATION HOLDS ACROSS ALL MAMALLIAN SPECIES). PLC --> DAG + IP3 --> Ca2+

When sperm and egg combine to form a 2-cell embryo capable of full term development.

Cortical granule exocytosis...extrusion of 2nd polar body. Cleavage to 2-cell stage.
What process prevents polyspermy?
When sperm enters egg, cortical granules are released into perivitelline space.
What sperm protein is involved in egg activation and drives calcium oscillations?
PLC - gamma.
What is the signifance of calcium oscillations?
PLC - gamma mediated Ca2+ oscillations drive development further as noted with increasing amounts of expelled cortical granules.
When does the zygote stop dividing and instead start growing?
Not until it hatches from ZP (during implantation)
How are microtubules in sperm arranged?
in a 9+2 formation.
true/false

Trip from ejaculation to fertilization is always long
FALSE.

Can be as fast as 10 minutes.