Lecture 8: Neurolation Flashcards
What is Neurulation?
Neural plate —> neural tube
- starting point of CNS developments
How are the primitive streak, notochord, and neural plate connected?
Primitive streak regresses —> Notochord formation trails behind primitive streak regression —> regression forms neural plate for ectoderm to become CNS
Describe the Chordamesoderm role of induction on the neural ectoderm.
Chordamesoderm forms during gastrulation where it becomes the notochord and lies below the ectoderm prior to Neurulation
- signals from Chordamesoderm determines ectoderm as the neural ectoderm
Describe the Neurolation Events.
- thickening of neural ectoderm —> neural folds produce neural groove —> neural plate folds on itself where the anterior neuropore closes by the end of 4th week —> cells form neural tube —> Neural crest cells are formed during tube formation
What is the purpose of bottle cells in the process of Neurolation?
Allows neural plate to form neural tube
- interacts with microfilaments (F-actin) and microtubules
- if microtubule formation or F-actin formation is inhibited, bottle cells will not form properly
- Cytochalasin D disrupts actin microfilaments
- Colchicine inhibits microtubule polymerization
What is the Molecular process of neural plate formation by the Primative Node?
Primitive Node —> (neural induction signals to) Notochord (chordamesoderm) —> Noggin and Chordin inhibit BMP-4 expression to prevent neural ectoderm formation —> Neural Plate is formed
What are the embryonic cell lineages established at Neurulation?
What are the causes of Neural Tube Defects for certain disorders?
- abnormality due to errors in closure of neural tube; can array in severity
Anencephaly —> Failure of anterior neuropore closure
Spina bifida —> Failure of posterior neuropore closure
What is the cause of Spin bifida and how does it affect development?
- still suitable to survive life; no known exact cause but genetic and environmental factors may play a role
Can be in different regions:
80% in lower back
20% in upper regions (neck)
SB Occulta - “hidden”; mildest form where small separation or gap in one or more of the bones of the spine
SB Aperture - “open”
- meningocele
- myelomeningocele
Risk factors:
- folate (Vitamin B) deficiency
- family history with neural tube defects
- diabetes and obesity
Treatments:
- no cure but can prevent by undergoing surgery while still in womb
What is the cause of Anencephaly and its its effects on development?
- not suitable to survive life —> die with hours or days before or after birth
- missing large parts of brain
- Bones of skull are missing or incompletely formed
How does the Zika Virus contribute to Microcephaly?
- female Aded aegypti mosquito spread by feeding on blood to lay eggs
- for pregnant woman, the window of exposure for the most risk would be during the 1st trimester
- Zika can be transmitted from men and women to their sexual partners
