Embryonic Period 3-8 Weeks

Question 1

Teeth enamel is derived from what germ layer

Answer 1

Ectoderm

Question 2

Forelimbs paddle-shaped;
Nasal pits formed;
Embryo tightly C-shaped

Answer 2

Day 31-35

Question 3

Parathyroid derived from what germ layer

Answer 3

Endoderm

Question 4

Develops from somites

Answer 4

Bone, cartilage, muscle, dermis of the skin

Question 5

Central nervous system is derived from what germ layer

Answer 5

Ectoderm

Question 6

Sensory epithelium (ear, nose, eye) is derived from what germ layer

Answer 6

Ectoderm

Question 7

Dermatome (tissue)

Answer 7

Dermis of the skin

Question 8

Embryonic period (day 24-25) number of somites

Answer 8

13-20 somites

Question 9

Respiratory tract epithelial lining derived from what germ layer

Answer 9

Endoderm

Question 10

Embryonic epiblast produces what

Answer 10

Primitive streak
Ectoderm

Mesoderm
Primordial germ cells

Endoderm

Question 11

Fourth visceral arch formed;
Hind limb buds appear;
Otic vesicle and lens placode

Answer 11

Day 28-30

Question 12

GI tract epithelial lining derived from what germ layer

Answer 12

Endoderm

Question 13

Embryonic period (day 28-30) number of somites

Answer 13

30-35 somites

Question 14

Digital rays in hand and foot plates;
Brain vesicles prominent;
External auricle forms from auricular hillocks;
Umbilical herniation intiated

Answer 14

Day 36-42

Question 15

Number of somites that appear during Day 20-21

Answer 15

1-4

Question 16

Auditory tube epithelial lining derived from

Answer 16

Endoderm

Question 17

Pancreas derived from what germ layer

Answer 17

Endoderm

Question 18

Day(s) the notochordal process appears

Answer 18

Day 16-18

Question 19

Tympanic cavity epithelial lining derived from

Answer 19

Endoderm

Question 20

Embryonic period (day 20-21) number of somites

Answer 20

1-4 somites

Question 21

Embryonic period (day 26-27) number of somites

Answer 21

21-29 somites

Question 22

Connection with yolk sac and placenta maintained through

Answer 22

Vitelline duct and umbilical cord, respectively

Question 23

Skin, hair, nails is derived from what germ layer

Answer 23

Ectoderm

Question 24

Liver derived from germ layer

Answer 24

Endoderm

Question 25

``` Limbs long, bent at elbows, knees; Fingers, toes, free; Face more human like; Tail disappears; Umbilical herniation persists until the end of the third month ```

Answer 25

Day 50-56

Question 26

Somites appear

Answer 26

Day 20-21

Question 27

Embryonic period (day 22-23) number of somites

Answer 27

5-12 somites

Question 28

Intraemryonic mesoderm spread under cranial ectoderm; primitive streak continues; umbilical vessels and cranial neural folds begin to form

Answer 28

Day 19-20

Question 29

Notochordal process appears; | hemopoietic cells in yolk sac develop

Answer 29

Day 16-18

Question 30

Somitomeres are formed from

Answer 30

Paraxial mesoderm

Question 31

Day(s) the primitive streak appears

Answer 31

Day 14-15

Question 32

Connective tissue and bones of the face and skull derived from

Answer 32

Neural crest (ectoderm)

Question 33

Caudal neuropore closing or closed; Upper limb buds appear; Three pairs of visceral arches

Answer 33

Day 26-27

Question 34

Cephalocaudal folding under way; cranial neuropore closing or closed; optic vesicles formed; otic placodes appear

Answer 34

Day 24-25

Question 35

Pituitary gland derived from what germ layer

Answer 35

Ectoderm neural tube (posterior pituitary) / outer epithelium (anterior pituitary)

Question 36

Mammary and sweat glands are derived from what germ layer

Answer 36

Ectoderm

Question 37

Three components of the mesodermal germ layer

Answer 37

Paraxial, intermediate, lateral plate

Question 38

Three supporting tissues produced by somites (paraxial mesoderm)

Answer 38

Myotomes Sclerotomes Dermatomes

Question 39

Cranial neural folds elevated and deep neural groove established; embryo begins to bend

Answer 39

Day 20-21

Question 40

Myotome (tissue)

Answer 40

Muscle tissue

Question 41

Neural tube failure (cranial region)

Answer 41

Anencephaly

Question 42

Part of pituitary gland is derived from the neural tube of the ectoderm

Answer 42

Posterior pituitary

Question 43

Fusion of neural folds begins in cervical region; cranial and caudal neural folds open widely; visceral arches 1 and 2 present; heart tube begins to fold

Answer 43

Day 22-23

Question 44

Urinary bladder epithelial lining derived from what germ layer

Answer 44

Endoderm

Question 45

Mesenchyme of the head derived from

Answer 45

Somitomeres (paraxial mesoderm)

Question 46

Parenchyma of the thyroid derived from what germ layer

Answer 46

Endoderm

Question 47

``` Pigmentation of retina visible; Digital rays separate; Nipples and eyelids formed; Maxillary swellings fuse with medial nasal swellings as upper lip forms; Prominent umbilical herniation ```

Answer 47

Day 43-49

Question 48

Neural tube fails to close (cervical region caudally)

Answer 48

Spina bifida

Question 49

Sclerotome (tissue)

Answer 49

Cartilage and bone

Question 50

Peripheral nervous system is derived from what germ layer

Answer 50

Ectoderm