Embryology

Question 1

What is the name given to the parent gametes ?

Answer 1

spermatogonium and oogonium

Question 2

What does the process of meiosis produce in males and females?

Answer 2

Males - 4 sperm

Females - 1 egg + 3 polar bodies (which degenerate)

Question 3

Where does fertilisation occur?

Answer 3

The ovum

Question 4

What is a morula ?

Answer 4

The zygote undergoes mitosis to form a solid ball of cells

Question 5

What is a blastocyst?

Answer 5

The morula divides into two forming the trophoblast and an inner mass of cells. It also have an blastocyst cavity which nutrition can move into helping the cells to get nutrition.

Question 6

What do the layers in the blastocyst go on to form?

Answer 6

Trophoblast - Placenta

Inner ball of cells - Baby

Question 7

What is implantation ?

Answer 7

When the blastocysts buries itself in the endometrial lining. Controlled by the trophoblast which divides into two forming the chorion.

Question 8

What hormone foes the chorion produce?

Answer 8

HCG (Human chorionic gonadotropins)

Question 9

At what week does the placenta start supplying the baby with nutrients?

Answer 9

12

Question 10

What is the name given for the endometrial lining once’s the blastocyte has implanted?

Answer 10

Decidua basalis

Question 11

What is a bilaminar disc?

Answer 11

During implantation the inner call ball forms two layers which is called the bilaminar disc. This forms an upper cavity called the amniotic cavity and a lower cavity called the yolk sac.

Question 12

What are the two layer in the bilaminar disc called?

Answer 12

Epiblast and hypoblast

Question 13

What is a primitive streak?

Answer 13

The groove that is created which runs down the top of the bilaminar disc. (Epiblast)

Question 14

What are the three layers that are formed during gastrulation?

Answer 14

Ectoderm
Mesoderm
Endoderm

Question 15

Describe gastrulation

Answer 15

Cells from the epiblast migrate to lie between the epiblast and hypoblast forming the mesoderm.

Question 16

Describe neurulation

Answer 16

Cells of the ectoderm descend down and form a ball of cells which disconnects under the mesoderm and is called the notochord.
The primate chord thickens and forms a neural tube under the surface of the ectoderm.

Question 17

What happens after neurulation?

Answer 17

Mesoderm thickens and forms a paraxial mesoderm intermediate plate mesoderm and lateral plate mesoderm.

Question 18

What happens to the paraxial mesoderm ?

Answer 18

It divides into 3- the dermatome (Skin), myotome (muscles) and sclerotome (bones)

Question 19

Describe the folding that then takes place in the embryo?

Answer 19

The three layers fold round each other to create a tube.

Question 20

What layer will form the respiratory system?

Answer 20

The endoderm

Question 21

What is teratology ?

Answer 21

The study of things that go wrong in development

Question 22

Describe how the endoderm forms the respiratory system

Answer 22

Endoderm gives rise to the privative gut tube which has a hindgut, midgut and foregut. The trachea and lung buds form from the ventral wall of primitive foregut.

Question 23

How does the pleura form?

Answer 23

As the lung bud forms it pushes the splanchnic mesoderm towards the somatic mesoderm so that the lung bus is surrounded by both layers.

Question 24

Name the stages in the development of the respiratory system ?

Answer 24

Embryonic 
Pseudoglandual 
Canalicular 
Saccular 
Alveolar

Question 25

What happens in the Pseudoglandual phase (Respiratory)?

Answer 25

7-17 weeks

development of all lung structures except respiratory part

Question 26

What happens in the Canalicular phase (Respiratory)?

Answer 26

17-27 weeks
There is the formation of the respiratory part. Alveolar ducts form and epithelium starts to differentiate into Type 1 and type II pneumocytes

Question 27

What happens in the saccular phase (Respiratory)?

Answer 27

27 weeks - 40 weeks

Formation of the alveolar sacs, primitive alveoli and surfactant. Gas exchange begins.

Question 28

What happens in the alveolar phase (Respiratory)?

Answer 28

32 weeks - 8 years

proliferation of alveoli form alveolar sacs. 95% of adult alveoli are formed postnatally.

Question 29

From what does the diagram develop?

Answer 29

Mesoderm

Question 30

The diagram develops from 4 mesodermal structures, they are …

Answer 30

Septum transversum - forms the central tendon
Pleuroperitoneal folds - grown in from peripheries and fuse with septum
Skeletal muscle - Cover the pleuroperitoneal folds and forms the muscular part
Doral mesentery of the oesophagus - Forms the crura

Question 31

Name a few congenital lung conditions

Answer 31

• TOF or oesophageal atresia. The oesophagus has not correctly disconnected from the trachea.
• IRDS - Lack of surfactant
• Lung agenesis. Failure of lung development.
• Diagram isn’t completes closed (hernias) and hypoplasia (lack of growth).