Fertilization Flashcards
What is the purpose of capacitation?
Required for sperm to undergo acrosomal reaction
Where does capacitation occur in the female tract?
Inside the isthmus of the uterine tube
What enzyme is involved in penetrating the corona radiata?
Acrosin is the most important puts holes in the ZP allowing for sperm entry
What is the function of ZP3 in acrosomal reaction?
It is one of the four enzymes that make up the Zona Pellucida and ZP3 allows sperm to attach to the zona pellucida
Pronuclei vs Zygote
Pronuclei is the nuclear material of the head of spermatpzoan or oocyte after the oocyte has been penetrated by spermatozoan. Carries haploid set of chromosomes. Zygote is a fused sperm and egg and have established a diploid number of chromosomes.
What is the mechanism behind capacitation?
Removal of cholesterol from sperm surface and glyycoproteins
What parts of the sperm enter the cytoplasm of the oocyte?
Mitochondria, centrioles, and nucleus
What is fast block in relation to polyspermy?
Rapid depolarization of the egg plasmalemma that temporarily prevents entry of another sperm and gives time for slow block to occur.
What is slow block?
Release of polysaccharides from cortical granules under plasmalemma of egg. They become hydrated betwee ZP and Plasmalemma producing a swilling that prevents entry.
What is slow block?
Release of polysaccharides from cortical granules under plasmalemma of egg. They become hydrated between ZP and Plasmalemma producing a swilling that prevents entry.
What initiates the metabolic activation of egg?
Release of Ca ion with egg cytoplasms in response to introduction of phospholipids C zeta by sperm.
The released calcium blocks polyspermy.
What are the final steps in fertilization?
Metabolic activation of the egg
Decondensation of sperm nucleus
COmpletion of meiosis in the oocyte
Describe the penetration of the corona radiata?
Fusion of the outer acrosomal membrane with the sperm PM creates a portal through which contents of acrosome can be released. Hyaluronidase is one of the major enzymes in the acrosome.
What does Hyaluronidase do to aid in fertilization?
It diffuses out of the acrosome and dissolves the follicle cells of the corona radiata
How is the egg metabolically activated?
Initiated by the release of calcium ion within the cytoplasm in response to phospholipase C zeta by the sperm
What is decondensation of sperm nucleus
The sperm nuclear membrane becomes more permeable and allows entry of egg cytoplasmic factors that reduces disulfide cross links and chromatin becomes looser
What are the two pregnancy dating systems?
Fertilization age, which dates the age of embryo from time of fertilization. Menstrual age which dates the embryo from start of mothers last period. Two weeks greater than fertiliization age.
Which pregnancy dating system is greater?
Menstrual age is greater than fertilization
Post fertilization events?
Zygote becoms metabolically active, undergoes cleavage, embryo goes down uterine tube to uterus. Embryo looses ZP prior to implantation (hatching) Implants
