Anatomy, Embryology- Embryonic period(Week 4)

Question 1

Organogenesis

Answer 1

Formation of all organs from 3 germ layers.

Question 2

Morphogenesis

Answer 2

Formation of the shape and general body from the embryo. By folding of the trilaminar plate.

Question 3

Why is the embryonic period the most critical period of development?

Answer 3

• All organs begin to develop.
• The external body shape is formed.
• Congenital malformation usually occurs.

Question 4

List the 3 germ layers required for organogenesis.

Answer 4

1. Ectoderm
2. Endoderm
3. Mesoderm

Question 5

List the 3 germ layers required for organogenesis.

Answer 5

1. Ectoderm: Upper surface
2. Endoderm: Lower surface
3. Mesoderm: Middle surface

Question 6

Ectoderm is divided into

Answer 6

Neuroectoderm(Midline) and surface ectoderm(peripheral).

Question 7

What does the neuroectoderm form?

Answer 7

forms the neural tube and neural crest

Question 8

Notochord

Answer 8

It induces differentiation from overlying ectoderm to neuroectoderm.

Question 9

Derivatives of the neural tube.

Answer 9

• Brain
• Spinal cord
• Retina of eyes
• Posterior lobe of the pituitary gland.

Question 10

Derivatives of the neural crest.

Answer 10

Forms:

1. All ganglia
   a. Sensory Ganglia: Spinal and cranial.
   b. Autonomic: Sympathetic and parasympathetic
2. Pia mater and arachnoid
3. Schwann cells
4. Suprarenal medulla
5. Melanocytes
6. Odontoblasts
7. Facial skeleton

Question 11

What is sensory ganglia?

Answer 11

Spinal ganglia and ganglia of cranial nerve

Question 12

Where is neural crest located at?

Answer 12

Between neural groove and surface ectoderm.

Question 13

What do placodes consist of?

Answer 13

• Olfactory

- Otic

Question 14

What does olfactory placode form?

Answer 14

-Olfactory nerve and receptors.

Question 15

What does otic placode form?

Answer 15

-Vestibulocochlear nerve and receptors.

Question 16

What is surface ectoderm?

Answer 16

-Forms structures in contact with the outside world.

Question 17

What does surface ectoderm form?

Answer 17

1. Epidermis of the skin
2. Appendages of the skin
3. Sense organ
4. Anterior lobe
5. Salivary glands
6. Lower 1/2 of the anal canal.
7. Enamel of the teeth.

Question 18

What do the appendages of the skin consist of?

Answer 18

• Hair and nails.
• Sebaceous and sweat glands.
• Mammary gland.

Question 19

List the sense organs

Answer 19

• Eye: Lens and surface of the cornea.
• Ear: inner ear
• Nose: Epithelium of nasal cavity

Question 20

List the three-part intraembryonic mesoderm is divided into.

Answer 20

• paraxial mesoderm
• intermediate mesoderm
• lateral plate mesoderm

Question 21

What is the site of paraxial mesoderm?

Answer 21

• On each side of the notochord.

- Extends from the buccopharyngeal membrane to cleacal membrane.

Question 22

Intermediate mesoderm

Answer 22

• In the middle. It is called nephrogenic cord.

- Forms the urogenital system: kidney and gonads.

Question 23

Lateral plate mesoderm

Answer 23

Forms body cavities and body wall

Question 24

What is the division of the paraxial mesoderm?

Answer 24

Divides into segments called somites.

Question 25

What is the site of the paraxial mesoderm?

Answer 25

On each side of the notochord.

Question 26

Where does Paraxial mesoderm extend from?

Answer 26

Buccopharyngeal membrane to the cloacal membrane.

Question 27

What is the range of number of somites?

Answer 27

42-44

Question 28

What is the distribution of the somite?

Answer 28

- Occipital - Cervical - Thoracic - Lumbar - Sacral - Coccygeal

Question 29

How many somites are in the occipital?

Answer 29

4

Question 30

How many somites are in the cervical?

Answer 30

8

Question 31

How many somites are in the thoracic?

Answer 31

12

Question 32

How many somites are in the lumbar?

Answer 32

5

Question 33

How many somites are in the sacral?

Answer 33

5

Question 34

How many somites are in the coccygeal?

Answer 34

8-10

Question 35

What happens to the first occipital somite and the last 7 coccygeal?

Answer 35

They degenerates

Question 36

What are the 2 parts somite divides into?

Answer 36

- Sclerotome | - Dermomyotome

Question 37

What is a sclerotome?

Answer 37

Ventromedial part

Question 38

What is a dermomyotome?

Answer 38

The dorsolateral part

Question 39

What is dermomyotome divided into?

Answer 39

- Myotome | - Dermatome

Question 40

What is myotome?

Answer 40

Forms the muscles of the trunk.

Question 41

What is dermatome?

Answer 41

Forms the dermis of the skin

Question 42

What does the sclerotome form?

Answer 42

- Surrounds the notochord and neural tube. | - Forms the vertebrae.

Question 43

What are the 3 derivatives of the somite?

Answer 43

1. Sclerotome: Vertebrae 2. Dermatome: Dermis of the skin 3. Myotome: Muscles of the skin

Question 44

What is the origin of the skin?

Answer 44

Epidermis--> ectoderm | Dermis--> mesoderm

Question 45

What is the intraembryonic coelom?

Answer 45

Cavity in the lateral mesoderm.

Question 46

What are the 2 layers coelom divides the lateral plate into?

Answer 46

- Somatic layer | - Splanchnic layer

Question 47

What is the position of the somatic layer?

Answer 47

Below the ectoderm

Question 48

What is the position of the splanchnic layer?

Answer 48

Above the endoderm

Question 49

What does the lateral plate mesoderm form?

Answer 49

- Coelom - Somatic - Splanchnic

Question 50

How many cavities does the intraembryonic coelom form?

Answer 50

3 body cavities

Question 51

What are the cavities the intraembryonic coelom forms?

Answer 51

- Pericardial - Pleural - Peritoneal

Question 52

What is the pericardial cavity?

Answer 52

-Surrounds the heart

Question 53

What is the pleural cavity?

Answer 53

-Surrounds the lung

Question 54

What is the peritoneal cavity?

Answer 54

Surrounds the abdominal organs.

Question 55

What are the derivatives of the lateral plate mesoderm?

Answer 55

- Intraembryonic Coelom - Somatic layer - Splanchnic layer

Question 56

What does the somatic or parietal layer forms?

Answer 56

- Muscles of the body wall and limbs - Parietal layer of serous membranes: Peritoneum, pleura, and pericardium. - All forms of connective tissue.

Question 57

What does the splanchelic or visceral layer forms?

Answer 57

- Smooth muscles | - Visceral layer