Embryology: Germ Layers

Question 1

Label the following image

Answer 1

a. Zygoye
b. fertilized egg
c. Cleavage
d. Morula
e. Blasttula Embryoblast
f. 2 layer embryo

Question 2

How many weeks after ferlization foes the cell become the blastula/embyoblast? when does the 2 layer embryo form?

Answer 2

• Week 1
• Week 2

Question 3

when does gastrulation occur?

Answer 3

week 3

Question 4

what major events happen during this phase of embrology?

Answer 4

Folding, migration, growth, differentiation

Question 5

Label the diagram

Answer 5

a. coelom
b. yolk sac
c. somatic LPM
d. Nerve tube
e. notochord
f. coelom

Question 6

Label the diagram of the Bilaminar Germ Disc

Answer 6

1. Bilaminar Germ Disc
2. Developing Mouth
3. Primitive Streak
4. Epiblast
5. Hypoblast

Question 7

The epiblast cells migrate through the __________ to form which germ layers

Answer 7

• Primitive Streak
• to form all 3 germ layers (ectoderm, mesoderm, endoderm)

Question 8

Label this diagram of gastrulation (3 layer embryo)

Answer 8

1. Developing Mouth
2. Migrating Epiblast
3. Primitive Streak

Question 9

Is this step gastrulation or neurolation?

Answer 9

gastrulation

no notochord formation

Question 10

Label this diagraph of neurulation

Answer 10

a. Notochord induces neural folds
b. head
c. tail
d. primitive node
e. primitive streak

Question 11

Label the following diagram

Answer 11

1. Neural Folds
2. Future Neural Crest
3. Future neural tube

Question 12

the surface ectoderm becomes the _______

Answer 12

skin

Question 13

At the end of neuralation ______folding start forming

Answer 13

lateral

Question 14

label the following diagram

Answer 14

1. paraxial mesoderm
2. intermediate mesoderm
3. somatic laterial mesoderm (L.P.M)
4. Splanchnic L.P.M
5. Cardiac Tubes
6. Notochord Acial Mesoderm
7. Coelom

Question 15

______becomes the surface epithelium and neural tissue

Answer 15

Ectoderm

Question 16

______becomes the epithelium

Answer 16

endoderm

Question 17

______becomes all muscles and connective tissues, and some epithelia

Answer 17

mesoderm

Question 18

Label the following diagram

Answer 18

1. neural tube and crest
2. paraxial
3. Intermediate
4. lateral plate: arms (somatic and splanchnic)
5. somatic
6. splanchnic
7. embryonic coelom
8. ectoderm
9. endoderm tube

Question 19

Answer 19

This is a cross-section of germ layers as embryonic folding occurs

Question 20

Label this longitudinal section of the germ layers

Answer 20

1. ectoderm
2. neuroectoderm
3. endoderm
4. mesoderm

Question 21

the head to tail folding that occurs during embryonic folding at week 4 is called________

Answer 21

cephalocaudal folding

Question 22

What is embryonic folding?

Answer 22

formation of the gut and coelomic cavity

Question 23

which tissue can arise from all 3 germ layers?

Answer 23

epithelia

Question 24

connective tissue with the exception of the neural crest arises from _______

Answer 24

mesoderm

Question 25

Hair, fingerniail, tooth enamel, aweat glands, mammary glands arise from the \_\_\_\_\_\_\_

Answer 25

surface **_ectoderm_**

Question 26

What is the neural tube?

Answer 26

all the CNS (neurons and glial cells) ectoderm acons of motor neurons w/ cell bodies in the CNS

Question 27

What are the characteristics of the NCC?

Answer 27

* neurons w/ their cell bodies in the PNS, glial cells ofthe PNS (sensory neurons) * melanocytes in skin (pigment) * **connective tissues in the head** region-ectoderm (not mesoderm) * Ectoderm derived * forms: tooth dentine, adrenal medulla, great vessels of the heart

Question 28

failure of the \_\_\_\_\_\_migration can expalin the association of certain congenital anomalies (i.e. cleft palate and heart defects)

Answer 28

NCC

Question 29

Ectoderm

Answer 29

Surface ectoderm neural tube NCC-migrate all over the body

Question 30

Mesoderm

Answer 30

* intermediate mesoderm * lateral plate mesoderm * somatic L.P.M * Splanchnic L.P.M * Axial mesoderm * paraxial mesoderm * sclerotome * dermatome * myotome * epimere * hypomere

Question 31

Intermediate mesoderm

Answer 31

forms most of the urogenital system: kidneys, gonads, and ducts (not urinary bladder)

Question 32

Somatic L.M.P

Answer 32

outer tube conenctive tissues, blood vessels, smooth muscle parietal peritoneum, parietal pleura, and parietal pericardium

Question 33

Splanchnic lateral plate mesoderm

Answer 33

* inner tube connective tissues, blood vesels, smooth muscle * visceral peritoneum, visceral pleura, visceral pericadium mesenteries * heart and great vessels (w/ small contribution from neural crest)

Question 35

what does the axial mesoderm later form?

Answer 35

notochord

Question 36

what does the paraxial mesoderm later form?

Answer 36

somites (segmented)

Question 37

what does the sclerotome of the paraxial mesoderm form?

Answer 37

vertebrae and ribs

Question 38

what does the sclerotome fo the paraxial mesoderm later form?

Answer 38

dermis of the skin some (ventral) from the somatic L.P.M

Question 39

what does the myotome of the parazial mesoderm form?

Answer 39

all of the striated skeletal muscle

Question 40

what does the epimere of the epaxial muscle form?

Answer 40

all of the deep, midline, muscles of the back \*served by muscle RAMI (nerve) of spinal nerves

Question 41

what does the hypomere fo the myotome of the paraxial mesoderm form?

Answer 41

hypoxial muscel (all other muscle)

Question 42

Endoderm

Answer 42

Forms epithelia fo the gut tube & epithelia of gut tube derivatives such as lungs trachea, liver, pancreas, and urinary bladder