Cell development Flashcards
L18 L19
What are the (named) stages of embryonic development?
Unfertilized egg
Zygote (fertilized egg)
Morula
Blastocyst
What is cleavage?
The first round of divisions that occur in a fertilized egg.
What are the three germ layers?
Endoderm (inner)
Mesoderm (middle)
Ectoderm (outer)
What does the ectoderm give rise to?
Nervous system (CNS and PNS) Epidermis (Skin)
What does the endoderm give rise to?
Lungs
Gut
Pancreas
Liver
What does the mesoderm give rise to?
Kidneys Trunk skeleton Muscle Haemopoetic system (Heart and blood) Dermis (Layer below the skin)
What are the model organisms used to study development?
Rats/Mice Frogs Flies Flatworms Chicks Zebrafish
Pax6…
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What percentage of live born children have a congenital defect?
3-4%
What are the advantages to using mice to study development?
.
What are the advantages to using zebrafish to study development?
.
What are the advantages to using chicken to study development?
.
What are the advantages to using frogs to study development?
.
What are the advantages to using flies to study development?
.
What does the blastocyst consist of?
Inner cell mass which goes on to form the germ layer
Trophoblast which goes on to form the placenta
When is the organ system developed?
Between 3-8 weeks after fertilization
Why is the CNS underdeveloped at birth for humans?
Childbirth would be difficult if at birth the child was more developed.
When is an embryo most susceptible to birth defects?
Between 3-8 weeks with the 5th week being the ‘riskiest’ week.
What is a teratogen?
A factor which cause malformation of an embryo.
What is ‘transposition of the great blood vessels’?
How is it fixed?
It is when the aorta and pulmonary artery positions are are switched causing cyanotic heart disease in newborns. (cyanosis is a blue discolouration of the skin caused by deoxygenation)
To rectify this malformation, there is immediate heart surgery performed on the fetus to switch the great blood vessels to their proper positions.
What is ankyloglossia?
Congenital malformation of the tongue where the tip is attached to the floor of the mouth .
What does congenital mean?
Present at birth.
What is cleft palate?
Congenital malformation of the top of the lip where an opening or split is present due to tissues of this region not fusing together properly during prenatal development.
What is coloboma?
Congenital malformation where there is a hole in a part of the eye.
What is polydactyly?
Congenital malformation where additional fingers or toe have formed.
What is Down’s syndrome?
It is a congenital chromosomal defect where there is an extra copy of chromosome 21 causing a whole host of developmental defects. This includes:
Growth failure
Mental retardation and learning disabilities
Motor and sensory ability delay in development
It affects 1 in 1000 babies
What is cleidocranial dysostosis?
Congenital condition that primarily affects the bones and teeth. Severity ranges, but a common symptom is underdeveloped or absent collarbones.
What is thalidomide and what is its significance?
It is a medical drug that was used to ‘cure’ morning sickness during pregnancy. It was launched in 1957 and affected 12,000 children so was subsequently taken off market in 1961. It led to new FDA guidelines for testing drugs.
It is still used today as a medical drug to treat AIDS, leprosy and some cancers, but not for morning sickness
What are symptoms of fetal alcohol syndrome?
There is a wide range of symptoms between patients
Microcephaly (small head) Low nasal bridge Short nose Epicanthal folds Flat midface Thin upper lip Micrognathia (small jaw)
What is ‘Zika Virus’ and what are its symptoms?
A virus transmitted by mosquitoes.
Adults who are affected by the disease may have mild symptoms (fevers, rashes, headaches and muscle and joint pains) with symptoms lasting for 2-7 days, with some patients not even exhibiting symptoms.
Zika virus infection during pregnancy can cause infants to be born with microcephaly and other congenital malformations, known as congenital Zika syndrome.
NTDs…
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What can ectodermal defects lead to?
Defects in the... Hair Sweat glands Teeth Mammary gland (decreased milk production for females)
What can mesodermal defects lead to?
Defects in the…
Skeleton
Cartilage
Number of fingers and toes
What can endodermal defects lead to?
Defects in the…
Lungs
Esophagus
Gut
Lecture capture for the last few slides of L20
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What are neural crest cells?
They are multipotent stem cells in the skin that can differentiate to neurons, pigment cells, Schwann cells and smooth cells
