Development Embryopathy Flashcards
Why is it essential that only one sperm nucleus fuses with the egg nucleus during fertilization?
Extra chromosomes could cause severe developmental issues
One of the first organisms that was studied for developmental biology was the…
frog/xenopus
Cell-cell signalling is triggered by what?
Chemicals that are laid down in a track
Chemicals that are diffused to nearby cells
Chemicals that induce other cells
Mechanical signalling
In development biology, the gradient of ________ can trigger differentiation in cells
proteins/morphogens
Most developmental defects that occur ______ tend to be fatal
early
What sort of harmful substances does the placenta allow to pass?
Alcohol Drugs Nicotine Hormones German measles Lead mercury
What are 4 processes of embryogenesis?
- Cell migration
- Cell signalling
- Cell determination and differentiation
- Cell induction
Fusion of the sperm with the egg induces a wave of ________ ________ release. Where does this wave originate from?
intracellular calcium
Originates from the site of sperm-egg fusion
What is the general strategy that most organisms have to prevent more than one sperm fertilising an egg?
Block to polyspermy
__________ during gastrulation changes the embryo’s shape and cell arrangements
Morphogenesis
What are morphogenetic movements?
Cells changing shape during gastrulation
What are morphogenetic movements caused by?
Localised contractions of cells as well as cell movements. It involves rearrangement of the cytoskeleton and requires adhesion molecules
What is involution?
When cells at the site of the future blastopore change their shape
What are 3 things cell-cell signalling is responsible for?
- Regulating cell fate of nearby cells through induction
- Triggering cell contractions and elongations
- Controlling and directing cell migrations
What is embryopathy?
Developmental defects in an embryo or fetus
What are 2 examples of substances that can cause embryopathy?
Thalidomide
Alcohol
What is Thalidomide?
A drug developed in the 1950’s in Germany used to treat cancer, and some skin conditions
Why did scientists not realise Thalidomide caused embryopathy?
It was not tested in humans, and not even in pregnant animals
Why did pregnant women use Thalidomide?
Marketed to alleviate morning sickness
What were some defects of Thalidomide babies?
- Brain damage
- Deformed facial features
- Blind and deafness
- Short, twisted arms and legs
What is a teratogen? Is Thalidomide a teratogen?
Substances that cause defects in the embryo or fetus after the mother is exposed to it
Yes
How do most teratogen affect the embryo?
Crosses the mothers’ placenta and enters it
What is the placenta mainly used for?
Nutrient, gas, and waste exchange between mother and fetus
How does Thalidomide disrupt limb formation?
It inhibits signalling molecules essential for limb formation. Specifically, FGF10
Why did it take so long to discover that Thalidomide caused birth defects?
- Over 50 different names in 46 countries
- Contradicting drug information
- Symptoms similar to other diseases
- Pharma companies want to sell, sell, sell
What was an after effect of the Thalidomide crisis?
Tougher testing and licensing rules for drugs.
Why did the US avoid Thalidomide babies?
Frances Kelsey was sceptical of the drug and did not approve it. The drug was also known to have neural side effects
Drinking ________ in the first 2 weeks following fertilisation does not affect the zygote
alcohol
Why are fetuses affected by alcohol?
- No liver, meaning it cannot eliminate ethanol
- Re absorption through the amniotic fluid
Both lead to prolonged alcohol exposure, disrupting cell signalling
What are symptoms of FAS?
- Facial deformities
- Vision and hearing defects
- Deformed limbs and fingers
- Poor coordination
- Intellectual disability
