Capacitation And Fertilization Flashcards
What is capacitation? Where does it occur?
Requirement for sperm to undergo acrosomal reaction, happens in the uterine tube: isthmus
Sperm binds to tubal epithelium: cholesterol from sperm surface is removed and glycoproteins
What’s the enzyme responcible for breaking through the corona radiata?
Hyaluronidase in acrosome, breaks down intercellular matrix between the cells. Swimming movement also help
What is the function of ZP3 in the acrosomal reaction?
One of the four glycoproteins that make up the zona pellucida, attachment to ZP is mediated by ZP3 proteins and stimulates acrosomal rxn.
Influx of ca++ by sperm and exchange Na and H increases pH.
Acrosin
A serine protease. Needs for the complete penetration of zona pellucida
Digests a hole in the ZP
Not released by acrosome. Attached to sperm membrane
What’s the fast block to polyspermy?
Studied in sea urchins
A rapid depolarization of egg plasmalemma, -70 to +10mV in seconds
Temporary prevents slow blocks, allowing time for egg to establish slow block
Slow block to polyspermy
In sea urchins
Characterized by release of polysaccarides from the cortical granules located just under the plasmalemma of the egg
Polysaccaride enter perivitelline space (between plasmalemma and zona pellucida) and hydrat.
The swellling or hydration increases the space
What is the purpose of phospholipase C zeta?
It initiates the release of calcium that causes metabolic activation of the egg following fertilization
What does the released calcium after fetilization do?
Initiates blocks to polyspermy
Stimulates increase in egg respiration and metabolism via sodium-hydrogen ion exchange mechanism
Results in an increase in pH and an increase in oxidative metabolism
Pronuclei
Nuclear material of the head of the spermatozoan or of the oocyte after the oocyte has been penetrated by the spermatozoan
Haploid set of chromosomes
Male pronucleus consistes of decondensed nuclear material
Pronuclear membrane derived from endoplamic reticulum of the egg forms around the female chromosomal materia
Zygote
Single-cell stage where male and female prouclei have fused together and share and common membrane maing the chromosome number
What’s in vitro fertilization and how can it be used to treat infertiility?
Egg maturation is stimulated by hormones and eggs removed from ovary by laparoscopy
Sperm is collected and concentrated with the most active sperms and added to a petri dish with the eggs
Cleavage is achieved in vitro and about three embyros are implanted into the uterus.
Extra embryos are frozen.
Sperm that are unable to penetrated an egg can be artificially injected into an egg using special equipment.
What are the two ways pregnancy can be dated?
By Fertilization age: from time of fertlization
-how???? O.o o.O
By Menstrual age: age set from start of mother’s last menstrual period, two weeks greater than fertilization age.
