Mechanisms Of Disease During Embryogenesis Flashcards
What are the two main periods of human development?
Embryonic and fetal
When is the embryonic period and what happens in it?
Fertilisation -> week 8
When most of the organogenesis happens
When is the fetal period and what happens in it?
Week 8-> birth
Growth and modelling of organs
When does cleavage happen?
When zygote is moving from the site of fertilisation to the uterus
What is another name for the 16-cell zygote?
Morula
What is compaction?
The trophoblast secretes fluid inside, forming a blastocoele that pushes the inner cell mass to one side
-> inner cell mass splits into the hypoblast and the epiblast
In the morula, which cells are polar and what are their poles called?
Trophoblast cells have an apical and a basolateral surface
Inner cell mass are apolar
What is the blastocoele?
Fluid filled space secreted by trophoblast
What is the blastocyst?
Thing formed when the trophoblast has secreted the blastocoele and pushed the inner cell mass to the side
What does the inner cell mass split into?
Hypoblast and epiblast
Which part of the epiblast is touching the blastocoele?
Hypoblast
What happens once the embryo is fully implanted?
Formation of the bilaminar germ disk
What is gastrulation?
Differentiation from two layers of cells to three
What is another name for the hypoblast?
Primitive endoderm
What is the primitive endoderm displaced by in gastrulation?
Involuting cells that become the definitive endoderm and mesoderm
Where does the primitive groove form and what does it do?
One end of the epiblast and moves along the epiblast, displacing the hypoblast
What happens when the primitive streak reaches the other end of the epiblast?
It regresses
Where does the mesoderm form?
Between the epi and hypoblast
What does the hypoblast form?
Endoderm
What does the epiblast form?
Ectoderm
How is the notochord formed?
Primitive streak regression
What is the notochord?
A rod of cells that secrete molecules extracellularly that instruct the exoderm on top of it to become neural tissue
What forms the neural plate?
Notochord secretions
What forms the neural tube?
Folding of the neural plate
Where is the neural tube found?
Buried in the embryo (covered by surface ectoderm)
Where does neural tube formation start?
In the middle and moves out towards the edges
What does the ectoderm form?
Specification of the CNS
What does the mesoderm organise into?
Blocks called somites
What are somites precursors to?
Muscles and bones etc
What does folding of the embryo form?
Umbilical cord
What is happening at the same time as neurulation and somitogenesis?
Gut formation and body folding
What model does the embryo folding follow?
Cloth purse model
What happens in embyronic folding?
Septum and heart move from the margin to the centre
Yolk sac, allantois and stalk make the umbilical cord
What delimits the gut tube?
Prochordal and cloacal plates
What happens in organogenesis?
Differentiation of somitic derivitives Development of sensory organs Limb formation Formation of facial structures Formation of genital structures
What are the stages of development from egg -> adult?
Egg Fertilisation Cleavage Gastrulation Neurulation and somitogenesis Organogenesis Adult
Which limbs develop first?
Forelimbs
What is the establishment pattern of limb formation?
Proximodistal,
anterior-posterior,
dorsal-ventral
What are the desirable characteristics of a model organism?
Relevance/representitive Accessibilty/availibility Experimental manipulation Genetics Cost/space
What are specific gene mutations?
Cases when mutation in one particular gene will be enough to display a characteristic defect
What are chromosomal anomalies?
Whole chromosomal rearrangements responsible for a disease
What is an example of a chromosomal abormality?
Trisomy 21- downs syndrome
What is a polygenic disorder?
When several different genes are simultaneously affected, causing disease
What are environmental factors?
Deleterious influence of the environment on a particular process
