Embryology Development II Flashcards
What is gastrulation ?
Establishment of the three embryonic germ layers
What is the function of the of the 3 germ layers?
Layers from which all tissues of the body originate from
When is the embryonic period?
3-8 weeks after fertilisation
What is teratogenesis ?
Process by which congenital malformations are produced in an embryo/foetus
When is there the greatest risk of teratogenesis ?
During the embryonic period
Weeks 3-8 after fertilisation
Give some examples of teratogens ?
- warfarin
- isotretinon
- valproate acid
- thalidomide
Which virus can lead to teratogenesis ?
Rubella
What surface of the epiblast is the primitive streak formed?
Dorsal
Which week is the primitive streak formed?
Week 3 after fertilisation
How many days after fertilisation is the primitive streak formed ?
15-17 days
What is the name of the important structure that is formed in week 3 on the epiblast ?
Primitive streak
At the start of gastrulation how many layers are there and what are they called ?
2
Epiblast
Hypoblast
From which layer of the bilaminar disk is the trilaminar disk formed?
Epiblast
What are the name of the layers formed at the end of gastrulation ?
Ectoderm
Mesoderm
Endoderm
What is derived from the ectoderm ?
Epidermis
Nervous system
What is derived from the mesoderm ?
Muscle Cartilage Bone Heart Blood vessels
What is derived from the endoderm?
Epithelial lining of GI tract
Respiratory tract
Parenchyma of glands
What is situs inversus?
Heart and other organs develop on the wrong side of the body
What side of the body is the stomach and spleen on ?
Left
How many lobes does the left lung have?
2
How many lobes does the right lobe have?
3
Where on the primitive streak is the control centre for gastrulation ?
Which type of cells here determine what side organs grow?
Primitive node
Ciliated cells
When does gastrulation take place ?
3rd week of development.
What is neurulation ?
Development of CNS during embryonic period
When does neurulation occur?
Week 4
Which group of cells sends signals for neurulation ?
Where is this structure?
Where does it send signals too?
Notochord
Mesoderm
Ectoderm
What are somites?
Body segments
When in development does the first somite appear?
Day 20
Where does the first somite appear ?
Occipital region
At the end of week 5 how many pairs of somites are formed?
42-44
How many somites are there in humans ?
31 pairs
What are the 3 somite derivatives?
- dermatome
- myotome
- sclerotome
What is sclerotome a pre cursor of?
Bone
What is the buccopharyngeal membrane ?
Area of trilaminar disc with no mesoderm.
Area that ruptures to give opening of oral cavity
What are the 2 stages of folding of the embryo in week 4?
- cephalocaudal folding
- Lateral folding
What causes cephalocaudal folding to happen?
Growth of the neural tube
What causes lateral folding to occur?
Growth of the somites
Which type of folding happens in the saggital plane ?
Cephalocaudal
Which type of folding happens in the transverse plane?
Lateral
In which week of embryonic development does folding occur?
4th
