ToB 19 Embryology 3 - Mesoderm Flashcards Preview

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Flashcards in ToB 19 Embryology 3 - Mesoderm Deck (37)
1

Which germ layer present at the end of week 3 will give rise to the biggest variety of tissues and structures?

Mesoderm

2

Which germ layer present at the end of week 3 will give rise to tissues and structures that maintain contact between the inside and outside world? Ie: Brain, spinal cord, epidermis, retina etc.

Ectoderm

3

Which germ layer present at the end of week 3 will give rise to the neural tube?

Ectoderm

4

Why does part of the ectoderm layer become neuroectoderm?

The ectoderm directly above the notochord is changed to neuroectoderm via signal molcules released by the notochord.

5

The newly formed neuroectoderm forms a plate called:

Neural plate

6

How does the neural plate become the neural tube?

The notochord signals for the neural plate to thicken.

7

What shape is the neural plate?

Keyhole shaped

8

What is the name given to the part of the mesoderm layer which arranges itself around the neural tube?

Paraxial mesoderm

9

After formation of the neural tube, 4 different types of mesoderm are created. Name them:

1- Paraxial
2- Intermediate
3- Somatic
4- Splanchnic

10

What is the name of the u-shaped cavity which separates part of the mesoderm, creating the somatic mesoderm and splanchnic mesoderm?

Intraembryonic coelom

11

In which week after fertilisation does the neural tube and intaembryonic coelom form?

Week 4

12

Define splanchnic:

Relating to the viscera/ internal organs

13

What is the name of the part of the mesoderm layer which is segmented into somites?

Paraxial mesoderm

14

Define somite:

Bilaterally paired blocks of paraxial mesoderm which form along the head-to-tail axis

15

On which day after fertilisation do the first somites appear?

Day 20

16

Where do the first pair of somites appear?

Occipital region (base of skull)

17

Approximately how many somite pairs are present by the end of week 5 (after fertilisation)?

~ 42-44 pairs

18

The somites give rise to which tissue types?

1-Dermatome
2-Myotome
3-Sclerotome

19

Which 2 bone structures are formed from the Sclerotome?

1- Ribs
2- Vertebrae

20

What is the final number of somites formed?

31 pairs

21

What is the difference between the epimere and hypomere?

Epimere
- Formed from DORSAL myotome cells
- Innervated by DORSAL branch of spinal nerve
- Forms back muscles

Hypomere
- Formed from VENTRAL myotome cells
- Innervated by VENTRAL branch of spinal nerve
- Forms muscles of ventral body wall and limbs

22

The epimere is innervated by which branch of the spinal nerve?

Dorsal

23

The hypomere is innervated by which branch of the spinal nerve?

Ventral

24

The epimere will give rise to muscles where?

Back muscles

25

The hypomere will give rise to muscles where?

Ventral body wall and limbs

26

How many pairs of spinal nerves present in a body?

31 pairs

27

What can a single spinal nerve innervate?

The myotome or dermatome which differentiated from the same somite as the specific spinal nerve. (Same derivative)

28

How is there no overlap between the presence of spinal nerves?

Due to segmentation the spinal nerves can only innervate tissue from the same derivative (as the nerve)

29

What system does the intermediate mesoderm give rise to?

Urogenital system

30

What tissue doe the somatic mesoderm give rise to?

Connective tissue of limbs

31

What tissues does the splanchnic mesoderm give rise to?

Smooth muscle, connective tissue and vasculature of gut

32

What of the 3 germ layers grows the fastest?

Ectoderm

33

In which week after fertilisation does embryonic folding occur?

Week 4

34

What name is given to the embryonic folding that results in the head and tail end of the embryo to be folded under?

Cephalocaudal folding

35

What are the names of the 2 embryonic folds which create a body encased in ectoderm, with one opening for the umbilical cord?

1- Cephalocaudal folding
2- Lateral folding

36

Embryonic folding only creates one opening into the embryo. What is this opening for?

Umbilical cord

37

What event causes the embryonic disk to be suspended within the amniotic sac?

Embryonic folding