Embryology

Question 1

The epiblast cells all divide into what three layers?

Answer 1

ectoderm

mesoderm

endoderm

Question 2

What is the notochord?

Answer 2

The area of cells inside the mesoderm which cause differentiation and formation of different parts of the fetus

Question 3

What is gastrulation?

Answer 3

When the Ecto/meso/endoderm are formed

Question 4

How is the neural tube formed?

Answer 4

The notochord causes the ectoderm to fold inwards to for a neural tube and two neural folds either side, the folds come to together and seal off the neural tube which then fully dissociates with the rest of the ectoderm

Question 5

What is the process of the neural tube formation called?

Answer 5

Neurulation.

Question 6

By which day will the neural tube have formed?

Answer 6

By day 27

Question 7

Following the fusion of the neural folds, what cells leave to form the dorsal root ganglia on the lateral side?

Answer 7

The neural crest cells

Question 8

What three layers are formed by the neural tube?

What does each layer form?

Answer 8

A ventricular layer
- undifferentiated proliferative cells

A mantle layer
- Grey matter

A marginal layer
- White matter

Question 9

What is the alar plate and the basal plate

Answer 9

Alar plate is the dorsal area of the neural tube that forms the sensory area

Basal plate is the ventral area and forms the motor area

Question 10

Cranially how many vesicles does the neural tube develop into?

Answer 10

three

Question 11

What three vesicles does the neural tube develop into?

Answer 11

The forebrain (prosencephalon)

The Midbrain (mesencephalon)

The hindbrain (rhombencephelon)

Question 12

Which two of the first three vesicles of the neural tube then divide?

Answer 12

The forebrain (prosencephalon)

The hindbrain (rhombencephalon)

Question 13

What do the Forebrain and hindbrain of the neural tube then divide to form?

Answer 13

Forebrain (prosencephalon)

1. Telencephalon
2. diencephalon

Hindbrain (rhombencephalon)

1. Metencephalon
2. Myencephalon

Question 14

What do the Telencephalon and diencephalon (divisions of the forebrain) go on to form?

Answer 14

Telencephalon: cerebral hemispheres

Diencephalon: Thalamic and optic tissues

Question 15

What are the four forms of spina bifida?

Answer 15

Spina bifida occulta (common): small dimple visible, very rarely causes problems

Spina bifida meningocele: a sac containing meninges and CSF bulges out, there is little disability

Spina bifida myelomeningocele: bulging sac that contains nerves and spinal cord, damage and paralysis almost alway occurs.

Spina bifida Rachischisis: Developmental defect where the neural tube does not close properly, remains unfused and open.

Question 16

What are the thickenings of the pharyngeal foregut called, how many are there?

Answer 16

There are five, they are called the pharyngeal arches

Question 17

What do the pharyngeal arches contain?

Answer 17

Cartilage, muscle and an aortic arch artery, they also contain a cranial nerve (4 do).

Question 18

What does the first pharyngeal arch develop to become?

Answer 18

The lower and upper jaw.

Question 19

What does the second pharyngeal arch develop to become?

Answer 19

Hyoid bone.

Question 20

What are the pharyngeal clefts?

Answer 20

Ectoderm-lined separations of the pharyngeal arches.