Development

Question 1

steps of early embryogenesis

Answer 1

Fertilization, cleavage, gastrulation, neurulation, embryonic folding and organogenesis (see paper)

Question 2

3 events fertilization

Answer 2

sperm penetration and membrane fusion (through corona radiata zone and zona pellucida), egg activation, fusion of nuclei

Question 3

how does sperm penetration happen

Answer 3

acrosome of sperm contains digestive enzymes that drill through corona radiata zone and zona pellucida and then the sperm nucleus enters the eggs cytoplasm

Question 4

how does egg activation occur

Answer 4

release of Ca2+ where the egg coat is altered so sperm cant go in anymore, increase protein synthesis and rotation of cytoplasm

Question 5

how does fusion of nuclei occur

Answer 5

sperm and egg nuclei migrate towards and form diploid zygote

Question 6

cleavage

Answer 6

rapid division of zygote in blastomeres

Question 7

how are called the external and internal tissues in embryo

Answer 7

external: animal pole
Internal: vegetal pole

Question 8

how does the hollow ball of cells form (blastocoel)

Answer 8

blastomeres pump Na+ in intracellular spaces (the milk)

Question 9

cleavage pattern influenced by what

Answer 9

amount of yolk, at the poles there is most cytoplasm which is called the blastodisc and will reslut in embryo being not spherical (recall pic)

if a lot: meroblastic (incomplete) cleavage
If little: holoblastic (complete) cleavage

Question 10

do mammals have holoblastic or meroblastic cleavage and what does it mean for the shape of the embryo

Answer 10

holoblastic so embryo is spherical

Question 11

gastrulation

Answer 11

cell mvt in blastula to form 3 germ layers

Question 12

cell shape changes in gastrulation

Answer 12

invagination (making a tube), Involution (layer of cell moves towards side), delamination

Question 13

inner cell mass flattens and determines into ? layers

Answer 13

2

Question 14

Fates of primary germ layers

Answer 14

Ectoderm: epidermis skin, nervous system, sense organs
Endoderm: linning digestive and respiratory tracts, liver, pancreas, thymus, thyroid
Mesoderm: skeleton, muscle, blood vessels, heart, blood, gonads, kidneys, dermis of skin

Question 15

cell mvt through what gives rise to 3 primary germ layers

Answer 15

primitive streak

Question 16

organogensis and how does it occur

Answer 16

formation of organs, interactions with neighboring cells and 3 germ layers (so cell location determines its fate)

Question 17

organogensis in vertebrates

Answer 17

begins with neurulation where notochords (little point for support) and neural tube (big point above) develops (as spinal cord)

Question 18

days fertilization to birth

Answer 18

266 days

Question 19

4 extraembryonic membranes

Answer 19

Amnion (inside amniotic folding)
Choridon (contributes to placenta)
Yolk sac (food source for birds)
Alantois: in mammals blood vessels in umbilical cord, in birds gas exchange
YAAC

order: choridon, amnion, yolk sac, umbilical cord

Question 20

Week 1

Answer 20

clevage 30hr after fertilization, 6-7 days after differentiates into blastocyst, implantation

Question 21

Week 2

Answer 21

choridon+endometrium=placenta
proximity 2 bloods so gas exchange
gastrulation

Question 22

Week 3

Answer 22

Neurulation

Question 23

week 4

Answer 23

Organogenesis

Question 24

month 2

Answer 24

organogensis continues, small limbs, organs, wheighs 1g,

Question 25

week 9

Answer 25

fetus

Question 26

Month 3

Answer 26

nervous system, limbs move

Question 27

Month 4

Answer 27

bones enlarge

Question 28

when rapid fetal heart beat

Answer 28

2nd trimester

Question 29

3rd trimester

Answer 29

growth and organ maturation + major nerve tracts

Question 30

positive feedback in birth

Answer 30

uterus release prostaglandins=contraction=oxytocin=contraction=oxytocin=contraction…

Question 31

Birth stages

Answer 31

cervix relax so dilate
uteirne contraction so delivery
placenta expelled