Embryology

Question 1

When does gastrulation occur?

Answer 1

Third week of development, marking the start of the embryonic period

Question 2

What is gastrulation

Answer 2

Bilaminar disc, epiblast and hypoblast Converted into a trilaminar disk Ectoderm, mesoderm, endoderm

Question 3

How does gastrulation occur

Answer 3

Primitive streak forms in the epiblast, leading to migration and invagination of epiblast cells

Question 4

Why does gastrulation occur

Answer 4

To ensure the correct placement and precursor tissue to allow subsequent morphogenesis to take place

Question 5

How many weeks after fertilisation is the embryonic period

Answer 5

3 to 8

Question 6

teratogenesis Effects which stage of development the most and why

Answer 6

Pre-embryonic - lethal effects
embryonic - the most sensitive - As this period where systems were developed
fetal - less sensitive - period about growth and function maturation of systems

Question 7

What structure appears on epiblast layer during gastrulation

Answer 7

Primitive streak, with no laptop

Question 8

What happens to hyperblast layer in the formation of trilaminar disc

Answer 8

Is displaced, does not form any of the three layers of the trilaminar disc

Question 9

Name the three layers the epiblast differentiates into

Answer 9

Ectoderm
mesoderm
endoderm

Question 10

Which two parts of the trilaminar disc which are not 3 layers

Answer 10

Future anus and future mouth

Question 11

Ectoderm will feature develop

Answer 11

ecto= outside

Organs and structures that maintain contact with outside world
such as the nervous system and the epidermis

Question 12

Mesoderm future develop

Answer 12

Supporting tissues, muscle cartilage and bone vascular systems including heart and vessels

Question 13

Endoderm will future develop

Answer 13

Internal structures, epithelial lining of GI track, respiratory tract

Question 14

Immotile cilia can result in

Answer 14

situs inverters

Question 15

Howard left and right asymmetry produced

Answer 15

Ciliated cells at the node result in leftward flow of signal molecules. Site-specific signalling cascade initiated. Absence of signal results in right sidedness

Question 16

Which layer does the notochord form in

Answer 16

Mesoderm

Question 17

Notochord in neurulation leads to

Answer 17

Solid model cells running down the midline. Send signal to overlying ectoderm to differentiate into neur ectoderm.Electrical signal causes overlying ectoderm to thicken. Slip a shape neural plate Edges elevate out of the pain of the disc and card towards each other creating the neural tube

Question 18

Name of first cavity inside embryo

Answer 18

Intra embryonic coelom

Question 19

What do somites derived from

Answer 19

Pariaxial mesoderm

Question 20

Total number somites

Answer 20

31

Question 21

Somites broken down to form

Answer 21

Sclerotome - eventually form bone

Question 22

Folding in the head to foot plane is called

Answer 22

cephalocaudal Folding

Question 23

What is folding achieve

Answer 23

Draws together the margins of the disc
creating a ventricle body wall
pulling amniotic membrane around the disk
Embryo becomes suspended within the amniotic sac
pulling connected stalk ventrally

Fording allows everything to be put in my place

Question 24

Three stages from fertilisation to birth

Answer 24

The embryonic 1-2 weeks
embryonic 3-8 weeks
fetal 9-38 weeks
These are weeks post fertilisation

Question 25

Gestation age

Answer 25

Time since last menastration. Embryonic age +2 weeks

Question 26

Three stages of pre-embryonic period

Answer 26

Cleavage compaction implantation

Question 27

What is cleavage

Answer 27

Forms morula

Question 28

What is Compaction

Answer 28

Forms blastocyst

Question 29

Ideal location for fertilisation to occur

Answer 29

Anterior posterior ampulla of fallopian tube

Question 30

What you call a fertilised oocyte

Answer 30

Zygote

Question 31

Explain cleavage

Answer 31

``` Cleavage forms morula series of mitotic divisions begins 30 hours after fertilisation results into blastomeres of equal size zone of lucida glycoprotein shell ensures only one sperm fertilised egg ```

Question 32

During cleavage the cells can be described as

Answer 32

totipotent - Has the capacity to become any cell type

Question 33

What embryonic stage can create implantation genetic diagnosis account

Answer 33

morula In cleavage

Question 34

Explain compaction

Answer 34

Formation of first cavity full blastocyst inner cell mass - embryoblast Outer cell mass - Trophoblast

Question 35

Cells in compaction can be described as

Answer 35

Pluripotent the capacity to become one of many cell types

Question 36

What needs to occur before implantation can occur

Answer 36

Hatching, blastocyst hatches from zone pullucida | can now interact with uterine surface to implement

Question 37

How many cells does the conceptus have during implantation

Answer 37

Hundred, eight in Embryoblast and 92 trophoblast

Question 38

What happens in the week twos

Answer 38

Two distinct sailors emerge from the outer cell mass trophoblast x syncytiotrophoblast x cytotrophoblast inner cell mass embryoblast becomes bilaminar disk x Epiblast x Hypoblast

Question 39

Bilaminar disc

Answer 39

Epiblast and hypoblast

Question 40

What region of the uterus does implantation occur

Answer 40

Implantation is interstitial, uterine epithelium is breached and the conceptus implants within the uterine stroma

Question 41

Why does implantation occur

Answer 41

To establish maternal blood flow in the centre

Question 42

Basic structural units of materno-fetal exchange

Answer 42

Chorionic illness

Question 43

Conditions linked implantation defects

Answer 43

Ectopic pregnancies | centre Praevia

Question 44

abembryonic pole

Answer 44

Primitive yolk sac formed

Question 45

Embryonic pole

Answer 45

Rapid development of syncytitrophoblast

Question 46

which later is the yolk sac membrane in contact with

Answer 46

cytotrophoblast

Question 47

Primitive yolk sac membrane is pushed away from cytotrophoblast by

Answer 47

And a acelluar extra embryonic reticulm

Question 48

Which layer interacts with the maternal blood vessels

Answer 48

syncytiotrophoblast - Indeed maternal sinusoids

Question 49

What is the secondary yolk sack made from

Answer 49

The primitive yolk sac

Question 50

What Suspends embryo

Answer 50

Connecting Stalk

Question 51

What is the amniotic sac formed from

Answer 51

From from spaces within the epic last