Week 3- Formation of Germ Layers

Question 1

which embryonic week is characterized by rapid development from the embryonic disc to the actual embryo?

Answer 1

week 3 of development

Question 2

what three main things happen surfing week 3 of development

Answer 2

• primitive streak appears
• notochord develops
• three germ layers separate

Question 3

what are some frequent pregnancy symptoms

Answer 3

• nausea

- vomiting

Question 4

what does not rule out pregnancy because it could be caused by implantation bleeding?

Answer 4

vaginal bleeding

Question 5

what results from the leakage of blood into the uterine cavity from disrupted lacunar networks in the implanted blastocyst?

Answer 5

implantation bleeding

Question 6

what means the formation of the three germ layers

Answer 6

grastrualtion

Question 7

what are the three different germ layers

Answer 7

ectoderm
mesoderm
endoderm

Question 8

during grastrulation what happens to the bilaminar dic

Answer 8

it becomes a trilaminar dic

Question 9

what is morphogenesis?

Answer 9

the development of the embryos’s body form

Question 10

when is morphogenesis really significant?

Answer 10

during week 3 of development

Question 11

what are the 3 signaling proteins that play an essential role in grastualtin?

Answer 11

• BMP’s ( Bone Morphogenetic Proteins)
• FGFs (Fibroblast Growth Factors)
• Wnts

Question 12

which germ layer gives rise to

• epidermis
• PNS
• eye
• inner ear
• neural crest cells

Answer 12

ectoderm

Question 13

which germ layer is the source of

• epithelial linings of respiratory and digestive tracts
• liver
• pancreas

Answer 13

endoderm

Question 14

which germ layer give rise to

• skeletal system
• connective tissue
• dermis
• blood cells
• circulatory system

Answer 14

mesoderm

Question 15

what appears caudally in the median plane of the dorsal aspect of the embryonic disc

Answer 15

the primitive streak

Question 16

the cranial end of the primitive streak proliferates to form what

Answer 16

primitive node

Question 17

what happens to primitive streak overtime

Answer 17

it diminishes in relative size and becomes an insignificant structre

Question 18

when does the primitive streak usually disappear?

Answer 18

week 4

Question 19

what is sacroccygela teratoma?

Answer 19

this is when there is a remnant of the primitive streak and a tumor that contains tissues from all three germ layers is present (hair and teeth)

Question 20

which infants are most affected by sacroccygeal teratoma (80%)

Answer 20

females

Question 21

you can see a sacrococcygeal teratoma with what device?

Answer 21

sonograph

Question 22

the notochordal process is formed by cells that migrate through the streak when?

Answer 22

day 16 of embryonic development

Question 23

what are considered to be benign and malignant tumors that may form from vestigial remnants of notochrdal tissues

Answer 23

chordomas

Question 24

1/3 of chordomas occur where

Answer 24

at the base of the cranium and extend to the nasopharynx

Question 25

at what rate dies a chroma grow

Answer 25

slowly

Question 26

at day 16 what appears as a small sausage that is outpouching from the caudal wall of the umbilical vesicle that extends to the connecting stalk?

Answer 26

allantois

Question 27

the proximal part of the alantois that remains through development is called the

Answer 27

urachus

Question 28

what extends from the bladder to the umbilical region

Answer 28

urachus

Question 29

what is the urachus represented by in adults

Answer 29

the median umbilical ligament

Question 30

what are known as the remnants of the extraembryonic potion of the allantois, and are usually found between the fetal umbilical vessels and can be detected by ultrasound

Answer 30

allantoic cyst

Question 31

allantoic cysts are generally asymptomatic till when

Answer 31

childhood or adolescence because thats when they start running around a lot more

Question 32

what is the process involved in the formation of the neural plate and neural folds and closure of the folds to form the neural tube

Answer 32

neurulation

Question 33

durring neuraltion what may the embryo be referred as?

Answer 33

a nerurula

Question 34

the notochord induces the embryonic ectoderm to do what adjacent to the midline

Answer 34

it induces it to thicken and form elongated plate of epithelial cells called the neural plate

Question 35

the ectoderm of the neural plate (neuroectoderm) gives rise to what

Answer 35

CNS

Question 36

the neural folds are prominent where

Answer 36

at the cranial end of the embryo

Question 37

the cranial neural folds indicate what kind of development

Answer 37

brain development

Question 38

when do the neural folds move together?

Answer 38

by the end of week 3

Question 39

when the neural folds move together at the end of week 3 the neural plate turns into the...?

Answer 39

nerual tube

Question 40

what ganglia of cranial nerve cells derive in part from the mesoderm

Answer 40

CN V, CN VII, CN IX, and CN X

Question 41

the disturbance of neurulation may cause some abnormalities where

Answer 41

in the brain and spinal cord

Question 42

meroencephaly

Answer 42

partial absence of the brain

Question 43

3 neural tube abnormalities

Answer 43

- ancephaly - spina bifida - meroencephaly

Question 44

at the end of the 3rd week the paraxial mesoderm differentiates and divides into paired cuboidal bodies called?

Answer 44

somites

Question 45

by the end of the 5th week how many somites are there

Answer 45

42-44 pairs

Question 46

somites are the primordial for what

Answer 46

the skeletal system

Question 47

somites can help determine what

Answer 47

embryonic age (at 4- 5 weeks old)

Question 48

what does the somatic mesoderm and embryonic ectoderm form?

Answer 48

somatopleure, or embryonic body wall

Question 49

the splanchnic mesoderm and underlying embryonic endoderm for the embryonic gut also known as?

Answer 49

splanchopleure

Question 50

when will the intraembryonic coelm divide

Answer 50

by the end of the second month in three cavities

Question 51

what are the 3 cavities of the intraembryonic coelom

Answer 51

- pericardial cavity - pleural cavities - peritoneal cavity

Question 52

vasculogenesis and angiogenesis takes place when

Answer 52

at the beginning of week 3

Question 53

what is the development of blood vessels called?

Answer 53

angiogensesis

Question 54

why does the cardiovascular system form so early

Answer 54

because there is an urgent need for blood vessels to bring oxygen

Question 55

what is the early embryo called when the nerual tube is developing (third to fourth week)?

Answer 55

Neurula