3rd week and placental development

Question 1

Formation of germ layer

Answer 1

Gastrulation

Question 2

Formation of neural tube:

Answer 2

Neurulation

Question 3

Germ layer formation occurs in ___ sequence

Answer 3

cranio-caudal

Question 4

Prochordal plate is formed in the ___ region of the embryo

Answer 4

head region

Question 5

Prochordal plate is ____ cells of _____

Answer 5

columnar cells of hypoblast

Question 6

Prochordal plate forms:

Answer 6

buccopharyngeal membrane

Question 7

Primitive streak is formed in the:

Answer 7

tail end of the embryo

Question 8

Primitive streak is derived from the :

Answer 8

epiblast

Question 9

Primitive streak formation starts at the:

Answer 9

end of 2nd week or beginning of 3rd week (14th or 15th day)

Question 10

Indication of gastrulation

Answer 10

primitive streak formation

Question 11

Germ layer development:

a) 1st germ layer to develop:
b) 2nd germ layer to develop:
c) 3rd germ layer to develop:
d) 4th germ layer to develop:

Answer 11

a) endoderm (from epiblast)
b) intraembryonic mesoderm (from pritive streak)
c) ectoderm (remains of epiblast after the formation of IEM)
d) neural crest cell (NCC)

Question 12

Intraembryonic mesoderms spreads throughout the disc except:

Answer 12

prochordal plate and cloacal membrane

Question 13

All the germ layers are derived from:

Answer 13

epiblast > yolk sac

Question 14

At the tip of primitive streak, there is :

Answer 14

hensen’s node

Question 15

Invagination of the hensen’s node proliferation forms:

Answer 15

blastophore/ primitive pit

Question 16

From primitive pit forms:

Answer 16

notochord formation

Question 17

Fate of notochord:

Answer 17

disappears

Question 18

If notochord persists:

Answer 18

Chordoma formation

Question 19

Remnants of notochord:

Answer 19

nucleus pulposus> apical ligament of dens

Question 20

Role of notochord:

notochord stimulates formation of :

Answer 20

neural tube

Question 21

IEM divides into 3 layers:

Answer 21

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

Question 22

Undivided part of lateral mesoderm:

Answer 22

septum transversum

Question 23

Septum transversum contributes to the formation of:

Answer 23

1. diaphragm
2. liver- connective tissue, kupffer cells, sinusoids
3. fibrous pericardium

Question 24

Lateral mesoderm divides into:

Answer 24

splanchnopleuric layer and somatic layer of lateral mesoderm

Question 25

Paraxial mesoderm forms:

Answer 25

somites

Question 26

Intermediate mesoderm forms:

Answer 26

urogenital system

Question 27

lateral mesoderm forms:

Answer 27

body cavities- pleural, pericardial, peritoneal cavity

Question 28

Somatic layer of lateral mesoderm forms:

Answer 28

appendicular skeleton and parietal layer

Question 29

splanchnopleuric layer of lateral mesoderms forms:

Answer 29

cardiac and smooth muscles, visceral layer

Question 30

1st pair of somites appear:

Answer 30

on 20th day

Question 31

somites added each day:

Answer 31

3 pairs

Question 32

Number of somites by 5th week/35th day :

Answer 32

45 pairs (42-44 pairs)

Question 33

Sequence of formation of somites

Answer 33

occipital, cervical, thoracic, lumbar, sacral, coccygeal

Question 34

Number of somites after 5th week:

Answer 34

37 pairs since some somite sin the occipital and coccygeal region disappear

Question 35

Parts of somites:

Answer 35

sclerotome and dermomyotome

Question 36

Sclerotome forms:

Answer 36

axial skeleton- vertebra

Question 37

Sclerotome divided into:

Answer 37

ventral - forms body of vertebra
lateral - forms vertebral arch and ribs
dorsal - forms spine of vertebra

Question 38

Failure of fusion of ventral sclerotome:

Answer 38

hemivertebrae

Question 39

Failure of fusion of dorsal sclerotome:

Answer 39

spina bifida anomalies

Question 40

Dermomyotome divided into :

Answer 40

Dermatome: forms dermis of skin
Myotome: forms skeletal muscles

Question 41

Failure of fusion of dorsal sclerotome with tuft of hair over the defect:

Answer 41

spina bifida occulta

Question 42

Failure of fusion of dorsal sclerotome with the protrusion of meninges over the defect:

Answer 42

meningocele

Question 43

Failure of fusion of dorsal sclerotome with the protrusion of meninges with spinal cord in it

Answer 43

meningomyelocele

Question 44

Smooth muscles over dorsal aorta formed by:

Answer 44

splanchnopleuric layer of lateral mesoderm

Question 45

smooth muscles over iris is formed by:

Answer 45

neurectoderm

Question 46

smooth muscle over sweat and mammary gland is formed by :

Answer 46

surface ectoderm

Question 47

Smooth muscle over pharyngeal arch arteries is formed by:

Answer 47

NCC

Question 48

Formation of blood vessels is called:

Answer 48

angiogenesis

Question 49

Formation of blood vessels is by :

Answer 49

Mesodermal layers- splanchnopleuric+somatopleuric layer of EEM –> forms blood vessels (tertiary villi)

Question 50

Tertiary villi is formed by:

Answer 50

3rd week/ 21st day

Question 51

Anastomosis of blood vessels in the EEM with the IEM is called :

Answer 51

Tertiary villi

Question 52

Tumor of blood vessels(mesodermal layer)

Answer 52

Angioma

Question 53

Formation of blood cells:

Answer 53

hematopoiesis

Question 54

Hematopoiesis is done upto 5th week by:

Answer 54

splanchnopleuric layer of EEM

Question 55

Hematopoiesis is done from 5th week by:

Answer 55

liver, thymus, bone marrow, spleen

Question 56

Hematopoiesis in liver occurs upto:

Answer 56

7th month

Question 57

Placenta is contributed by 2 factors

Answer 57

maternal component: decidua basalis

fetal component: chorionic villi

Question 58

Uterine endometrium during pregnancy is called:

Answer 58

decidua

Question 59

Decidua between fetus and myometrium of uterus:

Answer 59

decidua basalis

Question 60

Decidua between fetus and uterine cavity:

Answer 60

decidua capsularis

Question 61

Remaining of decidua:

Answer 61

decidua parietalis