Exam 1 Structures/Germ Layer Fates

Question 1

What structures are identifiable in week 4?

Answer 1

1. neural tube
2. pharyngeal arches
3. forebrain
4. caudal eminence
5. upper limbs buds
6. otic pits
7. lens placode
8. lower limb buds
9. rudiments of CV system

Question 2

What structures are identifiable in week 5?

Answer 2

1. minor changes in body form
2. increased cranial growth
3. cervical sinus
4. some increased growth and development of existing structures, particularly limb buds

Question 3

What structures are identifiable in week 6?

Answer 3

1. upper limb buds show regional differentiation; large hand plates; digital rays
2. auricular hillock
3. external acoustic meatus
4. heart prominence prominent

Question 4

What structures are identifiable in week 7?

Answer 4

1. limbs continue to develop
2. communication between primordial gut and yolk sac decreases
3. intestines enter the extraembryonic coelom in the proximal part of the umbilical cord

Question 5

What structures are identifiable in week 8?

Answer 5

1. digits of hands are separated, but webbed
2. scalp vascular plexus becomes prominent
3. head still disproportionately large
4. neck region established
5. eyelids more obvious and close by end of 8th week due to epithelial fusion
6. auricles of the ear begin to take shape
7. some sex differentiation but inaccurate identification

Question 6

Epidermis arises from

Answer 6

surface ectoderm

Question 7

Hair arises from

Answer 7

surface ectoderm

Question 8

Nails arise from

Answer 8

surface ectoderm

Question 9

Cutaneous glands arise from

Answer 9

surface ectoderm

Question 10

Mammary glands arise from

Answer 10

surface ectoderm

Question 11

Anterior pituitary gland arises from

Answer 11

surface ectoderm

Question 12

Parenchyma of salivary gland arises from

Answer 12

surface ectoderm

Question 13

Enamel of teeth arise from

Answer 13

surface ectoderm

Question 14

Lens arises from

Answer 14

surface ectoderm

Question 15

Inner ear arises from

Answer 15

surface ectoderm

Question 16

Mesoderm divides into:

Answer 16

1. paraxial mesoderm
2. lateral plate mesoderm
3. intermediate mesoderm

Question 17

Epithelial component of trachea arises from:

Answer 17

endoderm

Question 18

Bronchi and lungs arise from

Answer 18

endoderm

Question 19

Epithelium of GI tract arise from

Answer 19

endoderm

Question 20

Urinary bladder and urachus arise from

Answer 20

endoderm

Question 21

Epithelial component of pharynx arises from

Answer 21

endoderm

Question 22

Thyroid arises from

Answer 22

endoderm

Question 23

Tympanic cavity arises from

Answer 23

endoderm

Question 24

Pharyngotympanic tube arises from

Answer 24

endoderm

Question 25

Tonsils and parathyroids arise from

Answer 25

endoderm

Question 26

Cranial and sensory ganglia and nerves arise from:

Answer 26

neural crest

Question 27

Adrenal medulla arise from:

Answer 27

neural crest

Question 28

Ectomesenchyme bones and skull arise from

Answer 28

neural crest

Question 29

Dentin arises from

Answer 29

neural crest

Question 30

Periodontal ligament arises from

Answer 30

neural crest

Question 31

Alveolar bone arises from

Answer 31

neural crest

Question 32

Posterior pituitary arises from

Answer 32

neuroectoderm

Question 33

Pineal body arises from

Answer 33

neuroectoderm

Question 34

Retina arises from

Answer 34

neuroectoderm

Question 35

CNS arises from

Answer 35

neuroectoderm

Question 36

Urogenital system arises from

Answer 36

Intermediate mesoderm

Question 37

Muscles of trunk and skeleton, except skull, arise from

Answer 37

paraxial mesoderm

Question 38

Dermis of skin arises from

Answer 38

paraxial mesoderm

Question 39

Connective tissue (mesenchyme) arises from

Answer 39

paraxial and lateral plate mesoderm

Question 40

Muscles of viscera arise from

Answer 40

Lateral plate mesoderm

Question 41

Serous membranes of pleura arise from

Answer 41

Lateral plate mesoderm

Question 42

Pericardium and peritoneum come from

Answer 42

Lateral plate mesoderm

Question 43

Blood and lymph cells arise from

Answer 43

Lateral plate mesoderm

Question 44

CV and lymphatic systems arise from

Answer 44

Lateral plate mesoderm

Question 45

Spleen arises from

Answer 45

Lateral plate mesoderm

Question 46

Adrenal cortex arises from

Answer 46

Lateral plate mesoderm