the first 3 weeks

Question 1

cleavage

Answer 1

series of mitotic divisions occuring over a three day period

Question 2

pronuclei forms a

Answer 2

zygote

Question 3

zygote forms a

Answer 3

morula

Question 4

layer of cells incarcerating cleavaging cells

Answer 4

zona pellucida

Question 5

why cants cells going through cleavage expand individually

Answer 5

incarcerated by the zoa pellucida

Question 6

morula forms the

Answer 6

blastocyst

Question 7

blastocyst contains

Answer 7

inner cell mass and trophoblast

Question 8

hatching

Answer 8

enzymatic breakdown of the zona pellucida

Question 9

why is the ovum a large cell

Answer 9

so that it can undergo cleavage without forming cells that are too small

Question 10

what is the trophoblast

Answer 10

cells lining the cavity in the blastocyst inside the zona pellucida

Question 11

first cells to interface with the uterus

Answer 11

trophoblast cells

Question 12

trophoblast will eventually become

Answer 12

the placenta

Question 13

trophablast divided into

Answer 13

cytotrophoblast and synsitiotrophoblast

Question 14

cytotrophoblast cell nuclei

Answer 14

single nuclei per cell

Question 15

syncytiotrophoblast cell nuclei

Answer 15

multiple nuclei per cell (cytotrophoblastic cells that have joined together)

Question 16

syncytium

Answer 16

giant multinucleated cells blending together

searches for maternal blood and uterine milk and absorbs nutrient via diffusion

Question 17

what has been achieved by week 2

Answer 17

fully implanted embryo

Question 18

lacunae of maternal blood and uterine milk

Answer 18

forms around the embryo and diffuses to help it grow

Question 19

extraembryonic mesoderm located

Answer 19

inside the cytotrophoblast cells

Question 20

Heuser’s membrane

Answer 20

thin layer of cells inside the extraembryonic mesoderm

Question 21

ventral means

Answer 21

toward the belly

Question 22

dorsal means

Answer 22

toward the back (spine)

Question 23

formation of the chorionic cavity

Answer 23

ventral extraembryonic mesoderm splits causing small cavities to form in the extracellular matrix which later fuse together to form the chorionic cavity

Question 24

3 cavities

Answer 24

amniotic cavity, yolk sac, chorionic cavity

Question 25

amniotic cavity located

Answer 25

dorsally

Question 26

chorionic cavity located

Answer 26

ventrally

Question 27

connecting stalk

Answer 27

created as the chorionic cavity grows and pinches off and joins dorsally to the amniotic cavity

Question 28

chorionic cavity also called

Answer 28

extraembryonic celoem

Question 29

division of the yolk sac

Answer 29

primary yolk sac breaks of and moves ventrally dude leaving the definitive yolk sac dorsally

Question 30

definitive yolk sac

Answer 30

only endoderm derived from the hypoblast (hypoblast is typically extraembryonic - this is the only hypoblast part that is found in the embryo)

Question 31

how does the embryo get nuttrient during the first three weeks

Answer 31

in the first three weeks it is small enough to survuve via diffusion

Question 32

chorionic villi

Answer 32

formed from EEM directed outward toward maternal capillary network carries fetal blood vessels outward to aid nutrient collection `

Question 33

gastrulation

Answer 33

formation of the three germ layers

Question 34

three germ layers

Answer 34

ectoderm mesoderm endoderm

Question 35

embryonic disk

Answer 35

where the epiblast and hypoblast layers are in contact

Question 36

epiblast

Answer 36

amniotic cavity side

Question 37

hypoblast

Answer 37

yolk sac side

Question 38

feature at the cranial end of the bilaminar disk

Answer 38

oropharyngeal membrane

Question 39

feature at the caudal end of the bilaminar disk

Answer 39

cloacal membrane

Question 40

primitive streak made up of

Answer 40

primitive groove, node and pit

Question 41

primitive groove

Answer 41

linear groove

Question 42

primitive node

Answer 42

head of primitive streak

Question 43

primitive pit

Answer 43

indent in the centre of the primitive node

Question 44

embryonic mechanisms

Answer 44

1. proliferate 2. differentiate 3. migrate 4. induction 5. combination

Question 45

proliferate

Answer 45

grow in cell number

Question 46

differentiate

Answer 46

alter developmental trajectory

Question 47

migration

Answer 47

cells move from one area to another

Question 48

induction

Answer 48

cause other cells or neighbouring cells to differentiate

Question 49

combination

Answer 49

whole organs are formed from different germ layers

Question 50

overexpression of cerberus protein causes

Answer 50

ectopic heads

Question 51

liver is made up of

Answer 51

mostly endodermal (biliary and hepatocytes) blood supply and some CT from mesoderm nerves from ectoderm

Question 52

epiblast migration

Answer 52

2 migrations of epiblast cells form the 3 germ layers

Question 53

migration occurs at

Answer 53

the primitive groove

Question 54

the first migration occurs during

Answer 54

days 14-15

Question 55

the first migration involves

Answer 55

piblast cells migrate and differentiate into endodermal cells § Displaces hypoblast from embryonic disk □ Hence why hypoblast is extraembryonic

Question 56

second migration occurs during

Answer 56

day 16

Question 57

second migration involves

Answer 57

- Epiblast cells migrate and differentiate into mesodermal cells - Remaining surface epiblast differentiates into ectoderm § Mesoderm separates ectoderm from endoderm □ Except for the oral and cloacal membranes ® Direct contact between them with no mesoderm

Question 58

remaining surface epiblast differentiaties into

Answer 58

endoderm

Question 59

direct contact between endoderm and ectoderm occurs at

Answer 59

oral and cloacal membranes

Question 60

mesoderm proliferates, differentiates and migrates forming

Answer 60

- Paraxial mesoderm - somites - Intermediate mesoderm - paired glands - Lateral plate mesoderm - body wall and gut tube wall

Question 61

paraxial mesoderm forms

Answer 61

somites

Question 62

intermediate mesoderm forms

Answer 62

paired glands (kidneys, etc.)

Question 63

lateral plate mesoderm

Answer 63

body wall and gut tube wall

Question 64

mesoderm from the pimitive pit differentiates into

Answer 64

notochord

Question 65

which direction does the notochord grow

Answer 65

toward cranial end

Question 66

what is nueralation

Answer 66

neural tube formation

Question 67

nueral tube formation

Answer 67

- overlying ectoderm proliferates and differentiates - creates a nueral groove - nueral cret cells fuse

Question 68

openings at each end of the notochord are called

Answer 68

nueropores

Question 69

tube cells are located

Answer 69

around the nueral canal

Question 70

tube cells form

Answer 70

brain and spinal cord

Question 71

crest cells will form

Answer 71

PNS

Question 72

surface cells form

Answer 72

skin/epidermis

Question 73

3 ectodermal developmental trajectories from nureal tube

Answer 73

tube cells crest cells surface cells

Question 74

caudal nueropore closure failure

Answer 74

spina bifida

Question 75

cranial neuropore closure failure

Answer 75

anancephaly