Embryology II

Question 1

At this point in the picture, what happens to the cells on top of the epiblast?

At this point in the picture, what happens to the cells that remain of the epiblast?

Answer 1

Cells on top detach, migrate, and form the mesenchyme

The remaining cells form the ectoderm

Question 2

The yellow that is directly under the mesoderm in the picture is from what? Is it from the hypoblast

So then where is the hypoblast?

Answer 2

No, it’s from the cells that migrated through the primitive streak

It’s the part that doesn’t directly underlie the mesoderm

Question 3

What does the migrating mesoderm (the red in the picture) become?

Answer 3

Connective Tissue

Question 4

The black boundary in the middle is also formed from migrating mesoderm, what structure does it form?

Answer 4

The notochord

Question 5

In the picture, the mesoderm that migrates along either side of the notochord is called the…

Answer 5

Paraxial Mesoderm

Question 6

In the picture below, what are I and S? Also note the location of the lateral plate mesoderm

Also, what is the space above the blue line?

Answer 6

1. I is the lateral plate mesoderm
2. S is the paraxial mesoderm
3. The space is the amniotic cavity

Question 7

What is the blue and the yellow in the picture below?

Answer 7

1. Blue is ectoderm
2. Yellow is endoderm

Question 8

What does the intermediate mesoderm form most of?

Answer 8

The urinary and reproductive system

Question 9

What is the name for the space that exists because of the split in the lateral plate mesoderm?

Answer 9

Intraembryonic Coelom

Question 10

What is the function/purpose of the space between the blue (ectoderm) and the outer intermediate mesoderm?

Answer 10

Supports the body wall with muscle and connective tissue

Question 11

What does the space between the mesoderms, formed by the lateral plate (the intraembryonic coelom) become?

Answer 11

Abdominal Cavity

Question 12

What does the space between the endoderm (yellow) become?

Answer 12

Gut Tube

Question 13

This is the term describing the part of the mesoderm that becomes the body wall

Answer 13

Somatopleure

Question 14

This is the term for the mesoderm that lines the outer part of the gut tube

Answer 14

Splanchopleure

Question 15

Identify the parts in this picture

Answer 15

Question 16

Identify the parts in this picture

Answer 16

Question 17

Identify the colored areas in this picture

Answer 17

Question 18

Which contributes most to the development of the notchord, ectoderm, mesoderm, or endoderm?

Answer 18

Mesoderm

Question 19

The notochord defines the ___ axis of the embryo

It induces the development of these two things

Answer 19

1. Defines the primordial axis of embryo
2. Induces the development of the neural plate
3. Induces development of axial skeleton

Question 20

What forms around the notochord?

What eventually happens to the notochord?

Answer 20

The vertebral column

It regresses and mostly disappears (except for intervertebral discs)

Question 21

The notochord loses its epithelial connection and becomes attached to the..

It then loses it’s epithelial connections once more and what happens ?

Answer 21

Endoderm

Cells at the end compact and it becomes a rod (see picture)

Question 22

The paraxial mesoderm forms the….

Answer 22

Somites

Question 23

1. These are the striated muscles of the body wall
2. They divide into two parts

Answer 23

Myotomes

Epimere and hypomere

Question 24

1. During segmentation, what folds in and creates neural tube?
2. What is within the neural tube (ventral to neural tube here)

Answer 24

1. Ectoderm
2. Notochord (ventral to NT here)

Question 25

The somites divide into three parts, what are they?

Answer 25

1. Scleratomes 2. Myotome 3. Dermatome

Question 26

Which aspect of the somite becomes cartitlage, supportive tissues, vertebrae and ribs

Answer 26

Scleratomes

Question 27

Which part of the somite forms muscles of body wall and limbs (trapezius, splenius, lats)

Answer 27

Myotomes

Question 28

1. The myotome divides into two parts, called... 2. This is the dorsal part of the myotome 3. This is the ventral part of the myotome

Answer 28

1. Epimere and Hypomere 2. Epimere 3. Hypomere

Question 29

This part of the myotome gives rise to the deep back muscles

Answer 29

Epimere

Question 30

This part of the myotome forms the ventral muscles and superficial back

Answer 30

Hypomere

Question 31

This part of the somite becomes the dermis

Answer 31

Dermatomes

Question 32

Identify the lines in this picture

Answer 32

Question 33

To form the dermis, the dermatomes join with what?

Answer 33

Somatopleure

Question 34

Identify the lines in this picture

Answer 34

Question 35

Scleretomes on either side grow towards one another, fuse, surround neural tube, form the...

Answer 35

Spinal Vertebrae

Question 36

These divide in half, top and bottoms of different ones fuse with one another, creating ones Why is this beneficial?

Answer 36

Scleratomes It allows muscles to span vertebrae, creating movement Also creates space for spinal nerves to travel

Question 37

During neuration, as shown in the picture, what structure is folding out? What does it form?

Answer 37

Ectoderm Neural plate

Question 38

During neurulation, what forms due to the rising of the lateral plate? The cells get thicker on at basal end but thinner at apical end

Answer 38

Neural groove and neural fold

Question 39

At this point in the picture, the ectoderm is well positioned to form the ___ but not the \_\_\_\_\_

Answer 39

1. Skin 2. Brain

Question 40

1. When the neural folds reach eachother, where does fusion begin? 2. What does this fold and fusion eventually form?

Answer 40

1. In the middle, the fuses away from middle in cranial and caudal direction 2. Neural Tube

Question 41

What does the neural tube form?

Answer 41

CNS and somatic efferent (motor) neurons

Question 42

Within the neural fold, these detach, migrate and become other nervous system processes (afferent neurons, dorsal root ganglia, much of ANS and ganglia, glial cells, many cells in endocrine and other body systems)

Answer 42

Neural crest cells