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Flashcards in Fertilisation & Conception Deck (24):
1

Name FOUR factors which can influence fertility

Hormonal
Structural
Drugs
Environmental & Lifestyle

2

Name the NINE stages of conception

Cervical Mucus Changes
Sexual Intercourse
Capacitation
Acrosome Reaction
Penetration of Zona Pellucida
Fusion of the Oocyte and Sperm
Cortical Reaction
Zona Reaction
Fertilisation

3

Following fertilisation (day 0), describe the changes that occur through to the end of day 9

DAY 1
The fertilised egg or zygote undergoes cleavage

DAY 2
It has developed to the 2-cell stage

DAY 3
It has developed to the 4-cell stage

DAY 4
Changes from an 8-cell UNcompacted morula to an 8-cell COMPACTED morula

DAY 5
Has developed into an early blastocyst with an inner cell mass

DAY 6-7
Developed into a late-stage blastocyst and zona pellucida falls away

DAY 8-9
Implantation of the blastocyst occurs

4

When does the Acrosome Reaction occur?

As the sperm contacts the Zona Pellucida

5

Which reactions block any additional sperm from entering the oocyte?

The Cortical Reaction and the Zona Reaction

6

What is capacitation?

The process of maturation of sperm when glycoproteins are removed from the surface of the acrosome cap while it travels through the uterus or uterine tubes

7

Describe the Acrosome Reaction

The lytic (digestive) enzymes from many sperm disperse the corona radiata allowing the head of one sperm to make contact with the zona pellucida

8

Describe the Cortical Reaction

This process consists of the secretion of cortical granules into the space between the plasma membrane and the zona pellucida This renders the membrane of the oocyte impermeable for other sperm cells.

9

Describe the Zona Reaction

The reaction that occurs following the Cortical Reaction, which prevents other sperm cells from penetrating the membrane of the oocyte

10

How often do cell divisions occur?

Every 12-15 hours

11

Name the FOUR components of a blastocyst

1. Zona pellucida – thick glycoprotein membrane
2. Trophoblast – one cell thick, outer layer of cells
3. Inner cell mass – 1-2 cell thick, crescent shaped cluster of cells
4. Fluid filled cavity

12

What is Gastrulation?

Inner cell mass differentiates into 3 layers after implanting when individual organs develop within the newly formed gem layers

13

What does the ECTODERM develop into?

The skin, nails, the epithelium of the nose, mouth and anal canal; the lens of the eye, the retina and the nervous system

14

What does the ENDODERM develop into?

The inner linings of the digestive tract, as well as the linings of the respiratory passages. It also forms many glands, such as the liver and pancreas.

15

What does the MESODERM develop into?

The somites, the notochord, and the mesenchyme, which give rise to the muscles, circulatory and excretory systems of the body.

16

When does the fetal heart start to beat?

At 22 days

17

When is the embryonic period?

From 2-8 weeks

18

When is the fetal period?

From 8 weeks to full term

19

From which week is the fetus fully formed?

At 29 weeks

20

What is the syncytiotrophoblast?

Inner layer of the trophoblast

21

What is the cytotrophoblast?

Outer layer of the trophoblast

22

By when is the placenta fully formed and functioning?

10 weeks

23

By when has the placenta reached full thickness?

16 weeks

24

By when is the placenta supplying all respiratory and nutritional requirements for the fetus?

19-20 weeks