Embryology

Question 1

weeks 0-3

Answer 1

conceptus/embryo

Question 2

weeks 4-8

Answer 2

embryonic period

Question 3

weeks 9-40

Answer 3

fetal period

Question 4

gametogenesis

Answer 4

formation of a gamete (oogenesis/ spermatogenesis)

Question 5

Fertilisation

Answer 5

fusion of sperm and oocyte to form zygote

Question 6

Cleavage

Answer 6

rapid period of cell division (mitotic division)

Question 7

gastrulation

Answer 7

formation of germ layers (ectoderm/mesoderm/endoderm)

Question 8

formation of body plan

Answer 8

embryonic folding

Question 9

organogenesis

Answer 9

formation of organ/ systems

Question 10

foetal period

Answer 10

growth and weight gain

Question 11

primary processes (6)

Answer 11

cell division
differentiation
cell attachment 
apoptosis
induction
cell migration

Question 12

secondary processes (2)

Answer 12

axis formation

folding/rotation

Question 13

control of development

Answer 13

genetic
epigenetic
environment (influencer)

Question 14

where does fertilisation take place

Answer 14

ampulla

Question 15

where does sperm bind during fertilisation

Answer 15

zona pellucida glycoprotein

Question 16

what substance released from sperm head digests its way into egg?

Answer 16

acrosomal enzymes

Question 17

what does sperm entry trigger? (2)

Answer 17

meiosis 2 and release of cortical granules by oocyte

Question 18

what is cleavage

Answer 18

first cell divisions

Question 19

the zygote undergoes a series of mitotic divisions which leads to many daughter cells called….

Answer 19

blastomeres

Question 20

what happens when there are 8 cells

Answer 20

compaction

Question 21

what does the zygote become after compaction

Answer 21

blastocyst

Question 22

define mosaicism

Answer 22

two or more cell lines with different chromosome complements

Question 23

what is the single celled thickness layer surrounding the blastocyst

Answer 23

trophoblast

Question 24

where does the blastocyst implant during implantation

Answer 24

uterine wall

Question 25

what is implantation driven by?

Answer 25

trophoblast

Question 26

where does the trophoblast attach to

Answer 26

endometrial epithelium

Question 27

what happens in week 1 of implantation

Answer 27

corpus luteum produces progesterone which maintains endometrial lining

Question 28

day 7.5?

Answer 28

trophoblast splits into the cytotrophoblast and the synctiotrophoblast

Question 29

describe the cytotrophoblast

Answer 29

inner part - individual cells

Question 30

describe synctiotrophoblast

Answer 30

invasive layer which will invade the endometrium to help implantation, single multinucleate cell

Question 31

what are the 2 layers of the embryo

Answer 31

epiblast (dorsal)

hypoblast (ventral)

Question 32

day 9?

Answer 32

implantation complete

2 cavities form: primitive yolk sac and amniotic cavity

Question 33

from what cells did the primitive yolk sac develop from

Answer 33

hypoblast

Question 34

from what cells did the amniotic cavity develop from

Answer 34

epiblast

Question 35

day 12?

Answer 35

chorionic cavity begins to form

Question 36

day 13?

Answer 36

chorionic cavity enlarges and definitive/ secondary yolk sac forms

Question 37

what is an ectopic pregnancy

Answer 37

implantation outside uterus (ie in ovary/perineum/uterine tube)

Question 38

week 3?

Answer 38

primitive streak appears in midline at caudal end of epiblast - ready for gastrulation

Question 39

what is gastrulation?

Answer 39

formation of germ layers

Question 40

how do the germ layers form

Answer 40

cells migrate from epiblast to primitive streak and drive down and populate hypoblast

Question 41

hypoblast cells are replaced by what?

Answer 41

definitive endoderm

Question 42

hypoblast cells make the….

Answer 42

endoderm

Question 43

epiblast cells make the….

Answer 43

ectoderm

Question 44

how does the mesoderm form

Answer 44

2 term layers become 3

Question 45

fate of endoderm

Answer 45

gut linings

Question 46

fate of ectoderm

Answer 46

epidermis of skin and nervous system

Question 47

fate of mesoderm

Answer 47

3 regions: paraxial mesoderm (axial skeleton/voluntary muscles/parts of dermis), intermediate (urogenital systems- kidney), lateral plate: somatic (dermis)/visceral (cv system)