Week 1 Pre-embryonic Stage

Question 1

Fertilization occurs when

Answer 1

A sperm and an ovum fuse in the ampula of the uterine tube

Question 2

The sex of the embryo is determined

Answer 2

Immediately after fertilization

Question 3

The outcome of fertilization are

Answer 3

1. Continuation of meiosis II
2. Determination of sex of the embryo
3. Formation of the zygote

Question 4

Capacitation

Answer 4

Takes place as the sperm travels to the ovum

Question 5

The duration of capacitation is

Answer 5

10 - 12 hours after ejaculation

Question 6

The reactions that take place at the ovum are

Answer 6

Axonal reaction and zonal reaction

Question 7

Mention the events that lead to fertilization of the ovum

Answer 7

1. The female must be ovulating stage of her menstrual cycle
2. Release of the ovum around day 14-15
3. Copulation takes place with a healthy male
4. The male ejaculates the sperm into the vagina of the female
5. The sperm begin to travel up the vagina into the uterine tubes.
6. The sperm undergoes capacitation due to the secretions of the uterine glands
7. The capacitated sperms then begin to burrow into the corona radiata surrounding the ovum.
8. Once at the zona pelucida the acrosome of the sperm binds to the zp receptor of the zona pellucida.
9. Binding causes the acrosome to burst open releasing its digestive enzymes into the zona pellucida allowing it to penetrate.
10. The sperm mixes its membrane with that of the ovum causing a zonal reaction to take place that decapacitates all the surrounding sperms.
11. The sperm nucleus then fuses with the ovum forming the zygote(single cell).