Development of the NS Flashcards
What is the carnegie system?
A classification system of early vertebrate development into 23 stages for better comparison between species
Howmany germ layers does a human zygote have by embryonic week 3?
3
What is the neural plate?
The thick medial part of the ectoderm, aka. the neuroectoderm
What is neurolation?
The formation of the neural tube
What are the three primary brain vesicles called, and what do they develop into respectively?
Prosencephalon –> forebrain
Mesencephalon –> mesencephalon
Rhombencephalon –> pons, medulla oblongata and cerebellum
What are the secondary brain vesicles, and what do they develop into respectively?
Telencephalon
Diencephalon
Mesencephalon
Metencephalon –> pons and cerebellum
Myelencephalon –> medulla oblongata
What is a flexure?
A bending of the neural tube
Where does the mitosis take place?
Close to the ventricular system
What is the sulcus limitans?
- A functional border between the sensory- and the motor system
- Divides the alar- and basal plate
- The caudal part of thee neural tube
Describe the development of the spinal cord.
Sulcus limitans –> central canal
Alar plate –> dorsal horn
Basal plate –> ventral horn
Where does the proliferation during the development of the cerebellum take place?
The proliferation takes place on the outer layer
Describe the development of the telencephalon.
Develops as lateral evaginations from the prosencephalon
Describe the development of the diencephalon.
Develops as the medial part of the prosencephalon
Where does the retina develop from?
The diencephalon
What does the thin dorsal and superficial telencephalon give rise to?
The cerebral cortex
What does the thick ventral and deep telencephalon give rise to?
The BG
How does the hippocampus migrate in the human telencephalon?
By sulci formation
What does a neural stem cell give rise to?
Neurons, oligodendrocytes and astrocytes
Where are the microglia developed?
In the immunesystem (yolk sac) migrating to the brain
What are spina bifida?
An incomplete closure of the neural tube, can be caused by lack of folic acid
How are the developmental transcription factors regulated, and how are the expression pattern?
Regulation maintained by positive/negative feed back loops, tightly regulated
Expression pattern: regional
What does the HOX genes control?
Segmentation of the spinal cord and the hindbrain, and A/P fate
What is early pattering of the neural tube based on?
Simple combinations of gradients
How are the combination gradient of WNT in the neural tube?
The more caudal, the more WNT
What are Noggin and SHH (sonic hedge hog) important for, and where are they secreted?
Neural tube formation
Secreted from notochord
What are SHH also important for?
Ventrilization and development of the two hemipheres
Describe the development of the segmented spinal cord.
Controlled by a dual RA:FGF8 gradient which continuously moves as each segment is formed (less RA the longer down the segments)
Describe the three zones of the midbrain.
Ventricular zone: proliferating progenitors
Intermediate zone: early postmitotic cells
Mantle zone: mature neurons
What are the functions of the radial glial cells during development?
Facillitate migration of newborn neurons, as they touch both surface of the brain
Neural stem cells
How are the cortical layer formed?
Deepest layers are formed first (inside-out development)
Why are rodents not a good model for development of the cortical layer?
Primatescortex is bigger, and primates posses an outer subventricular zone, which rodents does not
What are the progenitors of the PNS cells, and where are they formed?
Neural crest progenitor, formed in the most dorsal part of the neural tube
How are the NS finetuned?
“innervate or die” –> the target cells release specific survival factors when innervated
What is a growth cone?
A neurite outgrowth searching for the correct targt cell by chemoattraction/repulsion
What are formed first: neurons or glial cells?
Neurons - most glial cells are formed after birth
What are the main reason humans take longer to walk?
We lack oligodendrocytes when we´re born
What are the two sites of adult neurogenesis in rodents?
The subventricular zone, and the dentate gyrus of the hippocampus (memory)
Are there stem cells in the brain?
Yes, but very few, and not very active
What are pluripotent stem cells?
Embryonal stem cells –> can give rise to all cells in the body
What are the challenge of neural stem cells?
There are no “universal” neural stem cell, thus pattering must take place very early in neural differentiation
