Embryological Origins

Question 1

What process of cellular division creates gametes?

Answer 1

meiosis

Question 2

What are the names of mammalian gametes?

Answer 2

sperm and egg

Question 3

What sort of cells are gametes?

Answer 3

haploid

Question 4

During fertilisation what type of cell is created?

Answer 4

diploid cell

Question 5

When is sex determined?

Answer 5

when the first diploid cell is formed and the chromosomes are released into the ovum

Question 6

What is the first diploid cell known as?

Answer 6

zygote

Question 7

on what day does the first cell division happen in humans?

Answer 7

day 1/2 in humans

Question 8

what sort of cell division is occuring once the zygote is formed?

Answer 8

mitosis

Question 9

What happens to the size of the cells as mitosis continues in the zygote?

Answer 9

cells become smaller

Question 10

What is they zygote then known as?

Answer 10

morula

Question 11

What is the name of the edge of the uterus where the morula fuses?

Answer 11

isthmus

Question 12

What is the zona pellucinda?

Answer 12

outer shell of the morula

Question 13

What are totipotent cells?

Answer 13

cells that can become anything during differentiation

Question 14

What might totipotent cells be used for?

Answer 14

the embryo or the placenta

Question 15

What are pluiripotent cells?

Answer 15

cells that have differentiated but may form any tissue in the embryo

Question 16

What do the inner and outer cells of the morula become?

Answer 16

inner cells become embryoblast and the outer cells become trophoblast

Question 17

What will the trophoblast and embryoblast go on to become?

Answer 17

embryoblast-embryo and trophoblast-placenta

Question 18

What are the two types of differentiation found in stem cells?

Answer 18

undifferentiated or partially differentiated

Question 19

What type of cells are the most versitile as stem cells?

Answer 19

totipotent zygote cells

Question 20

What happens during implntation?

Answer 20

blastocyst attaches to the uterine wall

Question 21

What happens in species which carry litters?

Answer 21

the blastocysts spread evenly along uterine horns

Question 22

What two areas are created during embryoblast differentiation?

Answer 22

epiblast and hypoblast

Question 23

What does the epiblast contain?

Answer 23

amniotic cavity

Question 24

what does the hypoblast contain?

Answer 24

yolk sac

Question 25

what is a key feature of the outer layer of the trophoblast?

Answer 25

non antigenic

Question 26

What is the outerlayer of the trophoblast known as?

Answer 26

syncytiotrophoblast

Question 27

What is so important about the syncytiotrophoblast being non antigenic?

Answer 27

they interfere with maternal cells but are not rejected/trigger an immune response

Question 28

What are the combined epiblast and hypoblast known as?

Answer 28

bilaminer germ disk

Question 29

What is gastrulation?

Answer 29

formation of trilaminer germ disk and body tissue type cell derivative lines

Question 30

What are the three separate germ layers?

Answer 30

ectoderm, mesoderm and endoderm

Question 31

What are the three layers converted from?

Answer 31

epiblast and hydroblast

Question 32

How is the primative streak formed?

Answer 32

proliferating cells migrate to centre at caudal end

Question 33

Where does the primative streak originate from?

Answer 33

primative node

Question 34

What is the main group of cells that migrate through the primative streak?

Answer 34

epiblast

Question 35

What is the ectoderm formed from?

Answer 35

cells that remain in the epiblast

Question 36

what is the mesoderm formed from?

Answer 36

epiblast cells that migrate into the middle layer of bilaminer germ disc

Question 37

What is the endoderm formed from?

Answer 37

cells which displace the hydroblast

Question 38

What does the ectoderm go on to form?

Answer 38

central nervous system, peripheral nervous system, eyes ears and skin

Question 39

what does the mesoderm go on to form?

Answer 39

connective tissues, blood, bones and muscle

Question 40

What are the 3 subsections of the mesoderm?

Answer 40

paraxial mesoderm, intermediate mesoderm, lateral plate mesoderm

Question 41

What does the paraxial mesoderm form?

Answer 41

musculoskeletal system

Question 42

What does the intermediate mesoderm form?

Answer 42

urogenital systems

Question 43

What does the lateral plate mesoderm form?

Answer 43

muscular gut wall and partial body wall

Question 44

What does the endoderm go on to form?

Answer 44

GI tract organs, epithelium of GI and respiratory tract

Question 45

Why do all three layers form different things?

Answer 45

ectoderm is folded around the outside of embryo while endoderm is folded innermost

Question 46

What body system is developed during neuralation?

Answer 46

CNS

Question 47

What is formed during neuralation?

Answer 47

neural tube

Question 48

What is the notochord?

Answer 48

increase of poraxial mesoderm along the longitudanal axis of the embryo

Question 49

What does signalling from the notochord cause?

Answer 49

proliferation of mesoderm

Question 50

What does the proliferation of the mesoderm cause in ectoderm?

Answer 50

movement and change of shape in overlying ectoderm

Question 51

Where does neuralation begin and end?

Answer 51

begins centrally and moves cranially and caudally

Question 52

Describe the 4 stages of neuralation?

Answer 52

ectoderm changes shape creating neural grove over the notochord and neural folds on either side. neural groove becomes more pronounced as do neural folds. Neural crest cells form lateral to the top of the neural fold, neural crest formed at the most accute angle of fold. Neural crests meet and form neural tube, skin covers neural tube, neural crest cells present laterally to neural tube

Question 53

What do the rostral and caudal ends of the spinal chord form?

Answer 53

rostral: brain, caudal: spinal chord

Question 54

What can happen if the neural tube fails to close?

Answer 54

if rostrally/cranially: anecephally. If caudally: spina bifida or dermoid sinus

Question 55

What is anecephally?

Answer 55

open brain and lack of skull vault

Question 56

What other process is neuralation linked to ?

Answer 56

cell folding and growth

Question 57

In what directions does the cell grow?

Answer 57

laterally and caphalocaudal

Question 58

What does caphalocaudal mean?

Answer 58

head to toe

Question 59

What does lateral and caphalocaudal folding and growth lead to the formation of?

Answer 59

formation of body cavities and connecting stalk (connection with placenta)

Question 60

What happens during lateral folding?

Answer 60

ectoderm streached around the outside of the body (forms skin), yolk sac (endoderm) is pinched off, primative gut tube brought inside main embryonic cavity

Question 61

What happens during caphalocaudal folding?

Answer 61

amniotic cavity pulled down at cranial and caudal ends of embryo. Heart cells and tube are pulled inside the embryo