Fertilization

Question 1

What is the purpose of capacitation?

Answer 1

Required for sperm to undergo acrosomal reaction

Question 2

Where does capacitation occur in the female tract?

Answer 2

Inside the isthmus of the uterine tube

Question 3

What enzyme is involved in penetrating the corona radiata?

Answer 3

Acrosin is the most important puts holes in the ZP allowing for sperm entry

Question 4

What is the function of ZP3 in acrosomal reaction?

Answer 4

It is one of the four enzymes that make up the Zona Pellucida and ZP3 allows sperm to attach to the zona pellucida

Question 5

Pronuclei vs Zygote

Answer 5

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.

Question 6

What is the mechanism behind capacitation?

Answer 6

Removal of cholesterol from sperm surface and glyycoproteins

Question 7

What parts of the sperm enter the cytoplasm of the oocyte?

Answer 7

Mitochondria, centrioles, and nucleus

Question 8

What is fast block in relation to polyspermy?

Answer 8

Rapid depolarization of the egg plasmalemma that temporarily prevents entry of another sperm and gives time for slow block to occur.

Question 9

What is slow block?

Answer 9

Release of polysaccharides from cortical granules under plasmalemma of egg. They become hydrated betwee ZP and Plasmalemma producing a swilling that prevents entry.

Question 10

What is slow block?

Answer 10

Release of polysaccharides from cortical granules under plasmalemma of egg. They become hydrated between ZP and Plasmalemma producing a swilling that prevents entry.

Question 11

What initiates the metabolic activation of egg?

Answer 11

Release of Ca ion with egg cytoplasms in response to introduction of phospholipids C zeta by sperm.
The released calcium blocks polyspermy.

Question 12

What are the final steps in fertilization?

Answer 12

Metabolic activation of the egg
Decondensation of sperm nucleus
COmpletion of meiosis in the oocyte

Question 13

Describe the penetration of the corona radiata?

Answer 13

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.

Question 14

What does Hyaluronidase do to aid in fertilization?

Answer 14

It diffuses out of the acrosome and dissolves the follicle cells of the corona radiata

Question 15

How is the egg metabolically activated?

Answer 15

Initiated by the release of calcium ion within the cytoplasm in response to phospholipase C zeta by the sperm

Question 16

What is decondensation of sperm nucleus

Answer 16

The sperm nuclear membrane becomes more permeable and allows entry of egg cytoplasmic factors that reduces disulfide cross links and chromatin becomes looser

Question 17

What are the two pregnancy dating systems?

Answer 17

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.

Question 18

Which pregnancy dating system is greater?

Answer 18

Menstrual age is greater than fertilization

Question 19

Post fertilization events?

Answer 19

Zygote becoms metabolically active, undergoes cleavage, embryo goes down uterine tube to uterus. Embryo looses ZP prior to implantation (hatching) Implants