Physiological and Pathological formation of the brain and spinal cord 14.02.23 Flashcards
When does gastrulation occur?
3rd week
What does the ectoderm become?
- Skin
- Nervous system
What does the endoderm become?
- Epithelial lining of the gut and respiratory system
- Liver
- Pancreas
What does the mesoderm become?
- Notochord
- Muscular system
How does the neural plate form?
ectoderm thickens in midline
What is the first part of the spine to form?
The neural plate
How does the notochord form?
From mesoderm cells soon after gastrulation
How does the notochord start folding to form neural tube?
- Signals from notochord cause inward folding of ectoderm at the neural plate
- End of neural plate fuse and disconnect to form a neural tube
What are presumptive neural crest cells and where do they lie?
- They are presumptive because we don’t know exactly what they will become until they do
- They lie lateral to the neural groove
- Probably will form sensory ganglia, Schwann cells, adrenal medulla, meninges.
What gives rise to Melanocytes, Schwann cells and neurons?
The ectoderm
What gives rise to osteoblasts, adipocytes, chondrocytes?
The mesoderm
What do the neural crest cells form?
- Dorsal root ganglia of spinal cord
- Schwann cells
- Adrenal medulla
- Meninges
How do abnormalities of the spinal cord occur?
- Neural tube normally closes at end of 4th embryonic week
- Failure for this to close can cause neural tube defects
What are the environmental factors that can cause neural tube defects?
- Folic acid
- Maternal diabetes
(also can be family related)
What are the embryological regions of the brain?
- Prosencephalon
- Mesencephalon
- Rhombencephalon
(At 4 weeks)
What does the prosencephalon give rise to?
The telencephalon at 6 weeks
- Each section will subdivide into other neurological regions and eventually permanent structures of the brain
What does the prosencephalon become?
Cerebral hemispheres and thalamic structures
What does the mesencephalon become?
Midbrain
What does the rhombencephalon become?
- Becomes metencephalon and myelencephalon then…
- Medulla, pons, and cerebellum
What happens to neurons in the ventricular zone?
Stem cells found here which give rise to neurons
- Neurons migrate to outer surface of brain and stop along the way where they are needed for that function
- Neurogenesis
What is microcephaly and macrocephaly?
Micro: reduced head circumference
Macro: Increased HC
Where does CSF circulate?
Through subarachnoid space and through ventricles
What is the function of CSF?
Cushion the brain and help circulate metabolites away from brain
How is CSF absorbed?
Via arachnoid granulations
When does the development of sensation begin?
- Dermal skin innervated from 28 weeks
When does the BBB develop?
Begins forming at 8 weeks
How is the BBB formed?
From endothelial cells, pericytes and astrocytes
When should neural tube close?
End of 4th week
If not results in: spina bifida
