Cell Bio Lecture 13 - Development 2

Question 1

What percentage of a woman’s oocytes are actually ovulated in a lifetime?

Answer 1

0.01%

Question 2

What is overian hyperstimulation?

Answer 2

It is an inflammatory response that occurs after donating oocytes. Can occur in 10% of donors, and some of these result in inferfility.

Question 3

What are the top three causes of SAB?

Answer 3

1. Chromosomal abnormalities
2. Cleavage problems
3. Progesterone insufficiency

Question 4

How are the sperm aided in swimming up the cervical canal and later in the uterus? What is the workload (male vs. female)?

Answer 4

Muscular contractions and ciliary movements help the sperm. Women do 2/3 of the work, sperm 1/3

Question 5

What produces hCG, what does hCG do?

Answer 5

The embryo will produce hCG, which tells the corpus luteum to secrete progesterone to keep the uterine lining.

Question 6

For how long following fertilization does the corpus luteum have the responsibility of progesterone secretion?

Answer 6

20 weeks, then the mom and fetus take over.

Question 7

What is normal sperm concentration? How voluminous is a normal ejaculation?

Answer 7

100 million per mL, usually 2-6 mLs per ejaculation

Question 8

What sperm count is usually associated with infertility?

Answer 8

less than 10 million per mL

Question 9

What triggers uterine muscle contractions that help sperm?

Answer 9

Prostaglandins from the sperm

Question 10

What are the four important fertilization steps?

Answer 10

1. Capacitation
2. Acrosome reaction
3. Fusion with the plasma membrane
4. Cortical reaction

Question 11

Are freshly ejaculated sperm able to fertilize right away? Why or why not?

Answer 11

No, there needs to be removal of the glycoprotein coat and seminal proteins from the acrosomal surface. This is called capacitation and confers greater sperm activity.

Question 12

Describe the acrosome reaction.

Answer 12

The zona pellucida glycoprotein (ZP3) receptor on the acrosome binds the glycoprotein, which triggers release of enzymes that break down the follicular cell matrix and zona pellucida for entry into the oocyte.

Question 13

What is the official start of fertilization?

Answer 13

Plasma membrane fusion - the eureka moment

Question 14

What stimulates the secondary oocyte to complete Meiosis II?

Answer 14

Plasma membrane fusion with the sperm

Question 15

What is the ampulla?

Answer 15

Halfway down the fallopian tube where fertilization most often occurs.

Question 16

What is the cortical reaction?

Answer 16

Sperm-oocyte membrane fusion causes rapid exocytosis of cortical granules, which contain lysosomal enzymes that cross-link proteins in the zona pellucida so that more sperm cannot get in. Note: a wave of Ca 2+ is also a part of this that triggers exocytosis throughout the membrane.

Question 17

Describe the events immediately following fertilization.

Answer 17

1. Meiosis II finishes
2. Oocyte chromosomes condense and forms a pronucleus
3. Newly arrived sperm nucleus enlarges and forms the male pronucleus
4. The pronuclei fuse
5. All chromosomes replicate then line up for the first mitotic division

Question 18

What does polyspermy result in? What percentage of SABs is this attributed to?

Answer 18

Triploidy - 20% of SABs