Fertilization Flashcards
What two ways are sperm lost from the female tract?
Retrograde transport and Phogocytosis
What do sperm undergo when they encounter the oocyte?
Acrosome reaction and fertilization
What determines how much sperm is lost?
physical nature of ejaculate and site of deposition
Where is semen deposited in the cow and sheep?
Anterior vagina
Where is the semen deposited in the sow and mare?
Cervix
What is unique about the seminal plasma in a stallion and a boar?
It’s very viscous and may help reduce the retrograde flow from the tract. The boar creates coagulum.
How can the transport of sperm be divided?
Rapid and sustained phase
Which transport phase is best understood?
Sustained
How and where does the sustained phase deliver sperm?
Distally to the ovaries in a trickle fashion from reserves in the UTJ and cervix
E2 stimulates contractions of what during sperm transport?
Muscularis of the myometrium
What in the semen causes increased tone and motility of the uterus and oviduct?
PGF2a and PGE1
What is unique about the seminal plasma of a boar?
It contains a protein that advances the time of ovulation
Why would we choose to treat female pigs with compounds to minimize retrograde flow?
to alter the smooth muscle motility
What are the two types of cervical mucus made by the cow?
Sialomucin and Sulfomucin
Where are the two types of cattle cervical mucus produced and what is their viscosity?
Sialomucin- low viscosity and produced in the basal area of the cervical crypts
Sulfomucin- High viscosity and produced in the apical areas of the cervical epithelium
Describe the rapid phase of sperm transport.
The rapid phase delivers sperm to the site of fertilization but aren’t viable
Where does capacitation occur?
Cow and Sheep-as the sperm passes through the cervix
Sow and Mare- In the uterus and isthmus of the oviduct
Can a single environment capacitate all sperm types?
No
What goes through the marked biochemical changes during capacitation?
The plasma membrane of the sperm
What happens when sperm are removed from the female tract and placed into seminal plasma?
The become decapacitized again
What are the steps to fertilization after capacitation?
Hyperactive Motility Binding o the ZP Acrosome Reaction Penetration of the ZP Sperm oocyte membrane fusion Sperm engulfment Decondensation of sperm nucleus Formation of male pronucleus
Describe hyperactive motility
Occurs in the ampulla, causes them to move into a frenzied motion in search of the egg to increase contact
What are the 3 glycoproteins in the ZP of the oocyte?
ZP1, ZP2, ZP3
Which glycoproteins are considered structural?
ZP1, ZP2
What is the purpose of ZP3 glycoprotein?
binds to proteins on the sperm membrane
What two places are the sperm able to bind to on the egg?
Primary zona binding region
ARPR
When sperm binds at the ARPR what does the ZP3 do?
Initiate acrosome reaction
Where is the fusion protein and when is it activated?
At the equtorial segment
At vesiculation
Do Damaged acrsomes vesiculate in an orderly fashion?
No they rupture all at once
What purpose does acrosin serve?
Its an enzyme that hydrolyzes the zona proteins
Enhances sperm ability to bind
What is the perivitelline space?
Space between the zona and the oocyte plasma membrane
When is the spermatozoa engulfed in the process?
When the plasma membrane fuses with the equatorial segment
What do cortical granules contain?
mucopolysacchrides, proteases, perioxidase, acid phosphate, plaminogen activator
When do cortical granules move to the periphery of the oocyte cytoplasm?
During first and second meiotic divisions of oogenesis
What are the two blocks included in fertilization and what specifically do they do?
Vitelline block- cortical reaction reduces the ability of oocyte membrane to bind to other sperm
Zona block- Exocytosis prevents polyspermy
Describe the decondensation of the sperm nucleus.
Sperm nucleus enters the cytoplasm of the egg and becomes the male pronucleus.
Nucleus decondenses so that chromosomes pair up
What is sygamy?
Fusion of male and female pronuclei
