Embry 2

Question 1

What are the 3 roles of the notochord

Answer 1

1. establishes the longitudinal axis of the embryo and gives it some rigidity
2. provides signals for the development of axial MSK structures and the CNS
3. contributes to the intervertebral discs

Question 2

mesenchymal cells dive into the primitive pit and migrate cephalad, they form a cord called what?

Answer 2

notochordal process

Question 3

the notochordal process develops a lumen known as the ?

Answer 3

notochordal canal

Question 4

after the notochordal process approaches the prechordal plate, the floor of the process “fuses” with the ?. The notochordal process is now the ?

Answer 4

endoderm
notochordal plate

Question 5

notochordal plate -> notochord transition starts

Answer 5

cranially and progresses caudally

Question 6

the notochord induce the overlying ectoderm to develop into the ?

Answer 6

neural plate

Question 7

the prechordal plate develops into the ?

Answer 7

oropharyngeal membrane

Question 8

the oropharyngeal membrane has how many layer membrane?

Answer 8

ectoderm and endoderm, no mesoderm

Question 9

What forms caudal to the primitive streak

Answer 9

cloacal membrane

Question 10

how many layers are in the cloacal membrane?

Answer 10

two layers - ectoderm and endoderm, no mesoderm

Question 11

what is the future site of the anus

Answer 11

cloacal membrane

Question 12

what is allantois and what does it do?

Answer 12

small, vascularized diverticulum from the caudal wall of umbilical vesicle, extending into the connecting stalk
- functions in early blood formation and bladder develop, blood vessels become umbilical arteries

Question 13

notochord induces overlying ectoderm to form the ?

Answer 13

neural plate also known as neuroectoderm

Question 14

on day 18, the neural plate invaginates to form ?

Answer 14

the neural groove - neural folds are found on either side of the groove

Question 15

the neural folds eventually fuse together, and form the ?

Answer 15

neural tube

Question 16

what is neurulation

Answer 16

the process by which the neural tube is formed

Question 17

True or False: during the 3rd week, intraembryonic mesoderm proliferates to form a thick column of mesoderm on either side of the notochord

Answer 17

true

Question 18

what is paraxial mesoderm

Answer 18

right beside the notochord

Question 19

where is the intermediate mesoderm

Answer 19

just lateral to the paraxial mesoderm

Question 20

where is the lateral mesoderm

Answer 20

lateral to the intermediate mesoderm

Question 21

what are somites?

Answer 21

cuboidal masses of mesoderm on either side of the notochord, visible along the dorso-lateral surface of the embryo on each side of the neural tube, formed from the paraxial mesoderm

Question 22

during the 3rd week mesenchymal cells migrate anteriorly, lateral to the notochordal process to eventually form what?

Answer 22

cardiogenic mesoderm

Question 23

the primordium of the intraembryonic coelom (embryonic body cavity) appears where?

Answer 23

isolated spaces in the lateral mesoderm and cardiogenic mesoderm

Question 24

intra-embryonic coelom divides the lateral mesoderm into 2 layers which are?

Answer 24

• somatic or parietal layer of lateral mesoderm located beneath the ectodermal epithelium and continuous with the extraembryonic mesoderm
• splanchnic or visceral layer of lateral mesoderm next to the endoderm and continuous with the extraembryonic mesoderm covering the umbilical vesicle

Question 25

3 general structures in the region of the lateral mesoderm:

Answer 25

- somatopleure - splanchnopleure - intraembryonic coelom in between the somatopleure and splanchnopleure

Question 26

what is the somatopleure and where is it?

Answer 26

the somatic mesoderm and the overlying ectoderm, forms the body wall

Question 27

what is the splanchnopleure and where is it?

Answer 27

the splanchnnic mesoderm and the underlying intraembryonic endoderm, forms the embryonic gut

Question 28

during the 2nd month, the intraembryonic coelom develops into 3 main body cavities which are:

Answer 28

- pericardial cavity - pleural cavity - peritoneal cavity

Question 29

what is embryonic folding

Answer 29

the process by which a relatively "flat" embryonic disk becomes more and more cylindrical in shape

Question 30

folding occurs in 2 general planes which are?

Answer 30

the median plane and horizontal plane

Question 31

describe embryonic folding in the median plane

Answer 31

anterior and posterior ends of the embryo move ventrally

Question 32

median plane is also known as?

Answer 32

cranial-caudal folding

Question 33

describe embryonic folding in the horizontal plane

Answer 33

the lateral edges of the embryonic disk move ventrally

Question 34

the horizontal plane is also known as ?

Answer 34

lateral folding

Question 35

what is the primordium of the mouth

Answer 35

stomodeum

Question 36

the position of the heart changes due to what?

Answer 36

the head fold

Question 37

lateral folding is caused by the rapidly growing what?

Answer 37

spinal cord and somites

Question 38

what are the 3 germ layers?

Answer 38

- ectoderm - mesoderm - endoderm

Question 39

the neural plate can been seen at what day?

Answer 39

day 19

Question 40

what line the central canal of the spinal cord?

Answer 40

ependymal cells

Question 41

the alar and basal plates of the developing spinal cord are separated by a groove called?

Answer 41

the sulcus limitans

Question 42

cell bodies in the alar plates form what?

Answer 42

the dorsal gray horns

Question 43

cell bodies in the basal plates form what?

Answer 43

ventral and lateral gray horns

Question 44

the unipolar neurons in the spinal ganglia (dorsal root ganglia) are derived from what?

Answer 44

neural crest cells

Question 45

fusion of the neural folds in the cranial region and closure of the rostral neuropore form 3 primary brain vesicles:

Answer 45

- forebrain (prosencephalon) - midbrain (mesencephalon) - hindbrain (rhombencephalon)

Question 46

during week 5, the prosencephalon partially divides into 2 secondary brain vesicles which are?

Answer 46

telencephalon and diencephalon

Question 47

by week 5, the rhombencephalon also partially divides into?

Answer 47

metencephalon and myelencephalon