L1a - embryology

Question 1

stages of development from oocyte to blastocyst

Answer 1

Oocyte > fertilisation > pronuclei > 2 cell stage > morula > advanced morula > blastocyst > implantation

Question 2

How long after the fertilisation does the stages of blatsocyst development occur

Answer 2

from 0 to 6 days

Question 3

how does dizygotic twins form

Answer 3

when the fertilised oocyte spilt in half to get 2 oocytes

Question 4

what is pronuclei

Answer 4

when male and female nuclei approach each other and fuse together

Question 5

what does the sprem contribute

Answer 5

centroiles

Question 6

what does the egg contribute to the zygote

Answer 6

mitochondria

Question 7

what is zona pellucida

Answer 7

• layer of prote ction surrounding the egg

Question 8

what happens once the zygote has reached 8 cell stage

Answer 8

forms inner cell mass (ICM) and outer cell mass (OCM)

Question 9

what does the ICM develop into

Answer 9

• epiblast (+ amniotic cavity)

- hypoblast (+ yolk sac) , forming an Embyro

Question 10

what does the OCM develop into

Answer 10

trophoblast then placenta

Question 11

what is pumped into the OCM forming blastocyst

Answer 11

fluid creating blastocyst cavity

Question 12

what is OCT4

Answer 12

TF

Question 13

function of OCT4

Answer 13

maintain pluripotentcy and involved in self renewal.

Question 14

what happens to the embyro if it lacks OCT4

Answer 14

no ICM and no pluripotency

Question 15

trophoblast differentiates into what layers

Answer 15

cytotrophoblast

synytiotrophoblast

Question 16

what is gestrulation and how long after fertilisation does it occur

Answer 16

early developmental process where the embryo reorganises itself to multi structure called gastrula

• 15 days

Question 17

what appears that initates gestrulation

Answer 17

primitive streak and primitive node

Question 18

what happens to the cell of epiblast when primitive streak appear

Answer 18

they migrate beneath it between epiblast and hypoblast Or
- displace the cells of hypoblast

• this migration forms gastrula layers

Question 19

what are the gastrula layers

Answer 19

endoderm
mesoderm
ectoderm

Question 20

what controls the epiblast cell migration forming the gastrula layers

Answer 20

FGF8

Question 21

FGF8 is synthesised by what

Answer 21

primiative streak

Question 22

endoderm develop further into what body strcutures

Answer 22

GIT, respiratory tract, urinary system

Question 23

mesoderm develop further into what body strcutures

Answer 23

connective tissue, cardiovascular system, blood cells

Question 24

ectoderm develop further into what body strcutures

Answer 24

Nervous system , teeth, epidermis

Question 25

what is formed after the gestrulation , 17-18 days after fertilisation

Answer 25

Notochordal plate comes from the endoderm and forms notochord

Question 26

function of notochord

Answer 26

important site for signal secretion for NS development

- located in mesoderm

Question 27

3 signalling molecules released by Primitive node

Answer 27

nodal, BMP4, chordin/nordin

Question 28

funtion of nodal

Answer 28

maintain primitive streak and upregulates BMP4 and chordin and noggin

Question 29

function of BMP4

Answer 29

• forms skin from ectoderm

Question 30

function chordin/noggin

Answer 30

block BMP4

- forms NS and cranial structures

Question 31

what gene is important for cranial development

Answer 31

GSC gene

Question 32

what protein does the GSC gene code for

Answer 32

goosecoid

Question 33

function of goosecoid

Answer 33

stimulates production of molecules like cerberus

- so the head can develop