Foetal Development Flashcards
What is a cordocentesis?
A cordocentesis is a procedure used to take a sample of fluid from the base of the umbilical cord.
List the events that occur in week 1 of gestation.
Week 1:
1 - Fertilisation.
2 - Blastocyst formation.
3 - Implantation.
What occurs in week 2 of gestation?
In week 2 of gestation, the bilaminar germ disc forms, comprising the epiblast and hypoblast.
What occurs in week 3 of gestation?
In week 3 of gestation, gastrulation occurs to form the trilaminar germ disc:
- Endoderm – formed by epiblast cells that migrate through the primitive streak and displace the hypoblast cells.
- Mesoderm – formed by epiblast cells that migrate through the primitive streak and lie between the epiblast layer and the newly created endoderm.
- Ectoderm – formed by the epiblast cells that remain in position.
- The hypoblast disappears.
What occurs in week 4 of gestation?
In week 4 of gestation, neurulation occurs (the transformation of the neural plate into the neural tube explain later in more detail).
List 2 tissues / organs that originate from the ectoderm.
The ectoderm gives rise to:
1 - The epidermis.
2 - Neural tissue.
List 5 tissues / organs that originate from the mesoderm.
The mesoderm gives rise to:
1 - Cardiac muscle.
2 - Skeletal muscle.
3 - Smooth muscle.
4 - Kidney tubules.
5 - Red blood cells.
List 6 tissues / organs that originate from the endoderm.
The endoderm gives rise to:
1 - Lungs.
2 - Thyroid gland.
3 - Pancreas.
4 - Liver.
5 - Colon.
6 - GIT.
How does the trilaminar disc fold to form a cylindrical embryo?
- Cephalocaudal folding occurs in the longitudinal direction.
- Lateral folding occurs in the lateral / transverse direction.
List the phases of foetal development (different to the phases of foetal growth as seen in the last lecture).
1 - Embryonic period (weeks 3-8):
- Organogenesis.
- Establishment of the main organ systems
2 - Foetogenesis (weeks 9-38):
- Maturation and growth of tissues.
List the types of birth defect.
1 - Structural birth defect.
2 - Functional birth defect.
3 - Metabolic birth defect.
What is the difference between a malformation, disruption and deformation?
- Malformation refers to abnormal formation of a structure.
- Disruption refers to alterations to an already-formed structure due to an intrinsic destructive process.
- Deformation refers to alterations to an already-formed structure due to an extrinsic mechanical factor.
What is the difference between a syndrome, association and sequence?
- A syndrome is a group of abnormalities which tend to occur together with a specific known cause.
- An association is a group of abnormalities which tend to occur together without a specific known cause.
- A sequence is a cascade of abnormalities.
Which chromosome is affected in Down’s syndrome?
Down’s syndrome is caused by trisomy of chromosome 21.
List 6 features of Down’s syndrome.
1 - Congenital heart defects.
2 - Duodenal atresia (closure of the duodenum).
3 - Learning difficulties.
4 - Early onset Alzheimer’s.
5 - Single palmar crease.
6 - Wide sandal gap.