Embryology

Question 1

What are the 3 major step in fertilisation

Answer 1

1) capacitation of the sperm
2) stem binding to the zona pellucida and releases nucleus. Lysosomal enzymes from cortical granules inactivate receptors
3) egg pronucleus and sperm pronucleus fuse

Question 2

What happens to the egg when it fuses with the sperms pronucleus

Answer 2

Undergoes meiosis 2 to from a zygote

Question 3

What are the specialisation of an egg

Answer 3

• mitchondria
• nucleus
• acrosome
• flagellum

Question 4

What is cleavage

Answer 4

Zygote forms a morula

Question 5

How many cells does a morula have

Answer 5

16

Question 6

When does cleavage occur

Answer 6

After the zygote has formed

Question 7

What happens when a morula is formed

Answer 7

The cells of the morula line to form a blastocyst

Question 8

What is a blastocyst made of

Answer 8

• trophoblast

- embryoblast

Question 9

What are the 3 layers of the uterus wall

Answer 9

• endometrium
• myometrium
• perimetrium

Question 10

What happens to the endometrium uterus wall

Answer 10

1) proliferative : estrogen levels are high
2) secretory : corpus leteum produce progesterone to produce compact, basal spongy layer and implantation occur
3) menstrual

Question 11

What happens to the trophoblast at implantation

Answer 11

Differentiates into

• cytotrophoblast
• synctiotrophoblast

Question 12

What happens to the embryoblast at implantation

Answer 12

Differentiates into

• hypoblast
• epiblast

Question 13

What happens to the syncitium when the egg has become implanted

Answer 13

Vacuoles appar called lacunae and blood inverts into it

Question 14

What does the cytotrophoblast do to the synctiotrophoblast

Answer 14

Create villus structures of primary, secondary and tertiary

Question 15

What does the hypoblast form

Answer 15

The primitive yolk sac

Question 16

What hormones does the synctiotrophoblast secrete when implantated

Answer 16

• hcg
• progesterone
• hPL

Take the role of the corpus leteum until birth

Question 17

What are the 4 placental barriers

Answer 17

• endothelium of villus
• synctiotrophoblast
• cytotrophoblast
• Loose connective tissue surrounding endothelium

Question 18

If there is a malignant tumour how can this be identified

Answer 18

It will show high levels of HCG

Question 19

What is gastrulation

Answer 19

The formation of the trilaminar disc

Question 20

How does gastrulation occur

Answer 20

• epiblast forms a primitive streak
• cells from the epiblast migrate underneath the primitive streak to form endoderm mesoderm
• remaining epiblast cells form ectoderm

Question 21

What occurs after gastrulation

Answer 21

Neuralation

Question 22

What is neuralation

Answer 22

The formation of the neural tube

Question 23

What happens at neuralation

Answer 23

Ectodermal cells migrate through primitive pit to from notochord
Notochord releases growth factor and ectoderm proliferate to from neural plate
Neural plate fold to from neural tube
Neural crest remain on top of the notochord

Question 24

When the notochord is formed which layer is it found at

Answer 24

The mesoderm

Question 25

What is the 4 role of the neural crest

Answer 25

1) form dorsal root ganglion 2) form neuro-endocrine cells e.g adrenal gland 3) melanocytes for skin colour 4) fascial mesenchyme

Question 26

How does the mesoderm develop

Answer 26

Split into 3 regions - paraxial - intermediate - lateral

Question 27

What does the paraxial mesoderm develop into

Answer 27

42-44 somites | Muscles

Question 28

What does the intermediate mesoderm develop into

Answer 28

Urogenital system

Question 29

What does the lateral mesoderm plate develop into

Answer 29

Heart

Question 30

What does the somites do

Answer 30

Form the vertebral column around the neural tube and notochord when sclerotome migrate Spinal nerves migrate out laterally to from the vertebral column

Question 31

How does the intermediate mesoderm form the urogenital sytem

Answer 31

Intermediate grow into - pronephros : this degrades - mesoneprhros: grows - metanephros: kidney develop here Gonads are form when germ cells migrate onto the intermediate mesoderm to from gonadal ridge which give gonads

Question 32

How does the action at the mesoderm differ in females and males

Answer 32

Male has mesonephric remains to form testis | Female has paramesonephric to form vagina

Question 33

What physical form does the lateral mesoderm split into

Answer 33

- somatic | - splanchnic

Question 34

What dos the splanchnic mesoderm develop into

Answer 34

The heart

Question 35

How is the heart derived

Answer 35

The progenitor cells of the splanchnic mesoderm from endocardial tubes Endorcardial tubes fuse together This forms the Ventura, atrium , ventricle, bulbous cordis and truncus ateriousus

Question 36

What happens to the atrium and the heart in further development

Answer 36

Portion into 2 chambers each

Question 37

If the heart does not portion out what can be a consequence of this

Answer 37

A hole in the heart

Question 38

Does the anterior or posterior plate form the heart

Answer 38

Anterior

Question 39

How does the heart get to its correct location in the body

Answer 39

By sagitall folding when the head and tail bend

Question 40

What are the two types of embryonic folding

Answer 40

- lateral | - sagitall

Question 41

What occurs when lateral folding takes place

Answer 41

- the gut tube forms

Question 42

How is the gut tube formed at lateral folding

Answer 42

The amniotic cavity folds laterally The yolk sac is pinched off to from the gut tube Body cavity is formed by the lateral plates

Question 43

How does the gut tube develop

Answer 43

Separates into 3 regions to derive - foregut: oesophageal and stomach - midgut : small intestine - hindgut : large intestine

Question 44

By what process does the neural tube develop

Answer 44

Vasiculation

Question 45

What does the neural tube develop into

Answer 45

The CNS

Question 46

What happens at vasciculation

Answer 46

Forebrain: - telencephalon - diencephalon Midbrain: - mesencephalon Hindbrain: - metencephalon - myelencephalon

Question 47

What does the telencephalon derive into further

Answer 47

Olfactory lobes Hippocampus Cerebrum

Question 48

What does the diencephalon develop into

Answer 48

Optic vesicle Epithalamus Thalamus hypothalmus

Question 49

What does the mesencephalon develop into

Answer 49

Mid brain

Question 50

What does the metencephalon develop into

Answer 50

Cerebellum | Pons

Question 51

What does the myelencephalon divide into

Answer 51

Medulla

Question 52

What are the 3 major neural tube defects of the brain

Answer 52

Hydrocephalus Microcephaly Anencephaly

Question 53

What is hydrocephalus

Answer 53

Water on the brain creates narrow slylvious and prevent blood blow to the blood vessels

Question 54

What is microcephaly

Answer 54

Small brain due to lack of forebrain induction

Question 55

What is anencephaly

Answer 55

Most of the brain absent due to from end of neural tube failing

Question 56

How can you identify neural tube defects

Answer 56

Look at high levels of alpha Fetoprotein

Question 57

What are the 3 main types of Spina bifida

Answer 57

Occulta Meningocele Meyelocoele

Question 58

What does Spina bidifa occur

Answer 58

As a result of not folding fully when the neural plates fold to create the neural tube

Question 59

At which structure does the future bladder develop from

Answer 59

Allantois

Question 60

How many pharyngeal pouches are there

Answer 60

4

Question 61

What does the first pouch give

Answer 61

Middle ear | Pharygontympanic tube

Question 62

What does the second pouch give

Answer 62

Palatine tonsil

Question 63

What does the third pitch give

Answer 63

``` Parathyroid gland (inferior) Thymus ```

Question 64

What does the 4th pouch give

Answer 64

Superior parathyroid | Small part of thyroid gland