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94 Cards in this Set

  • Front
  • Back
What is the number one cause of death during the first year of life?
Birth defects
What are the three major stages of development and when do they happen?
1. Zygotic: 0-14 days
2. Embryotic: 14 days to 8 weeks
3. Fetal: 8 weeks to 36 weeks
When are most neurons produced?
How much does the brain weigh at birth?
When does a majority of myelination occur?
What are the five stages of neurodevelopment?
1. Neurulation
2. Proliferation
3. Migration
4. Differentiation
5. Synaptogenesis
What is the neural tube the precursor for?
The neurons and glial cells of the CNS.
What is the PNS the made from?
Neural crest cells
What day in development does the blastocyst form?
Day 5
What part of the blastula becomes the embryo proper?
What does the placenta form from?
What day does the ICM delaminate?
Day 5
What part of the ICM becomes the embryo proper?
The epiblast
What part of the ICM becomes the yolk sack?
The hypoblast
What is the aggregation medially where the cells dive down in the epiblast?
Primitive streak or groove
What end of the epiblast does the primitive groove begin at?
The cranial end (Hensen's node)
What is the notochord derived from?
Axial mesoderm
What is the importance of the notochord in regard to neurodevelopment?
It induces the formation of the neural plate from the ectoderm.
What day does the neural plate form?
Day 18-19
Which end of the neural plate is wider and what will it give rise to?
The cranial end is wider and it will give rise to the brain.
What does the caudal portion of the neural plate give rise to?
Spinal cord
During primary neurulation, how does cell morphology change?
Cells take on a more pseudostratified character.
What is the area in the middle of the folding during neurulation called? What is it between? When does it form?
1. Neural groove
2. Neural folds
3. 18-19
When does closure of the neural tube occur? What area of the tube closes first?
1. Week 4
2. The midline
Where is the primary hinge joint in neurulation?
The midline
During wedging, how does a cell change its shape?
It widens at the basolateral end while narrowing at the apical end.
Where do secondary hinge joints occur in neurulation?
At what level does the neural tube start fusing?
The level of the 4th somite
Which neuropores fuse first, last?
1. Rostral
2. Caudal
What are the two phases of neurulation in higher vertabrates? What is developed in each stage?
1. Primary - brain
2. Secondary - formation of caudal structures
What causes the phenomenon of segmentation?
The change in cell to cell adhesion properties. Most likely tight junctions.
First segmentation produces what three vesicles?
1. Prosencephalon
2. Mesencephalon
3. Rhombocephalon
What causes the actual differentiation in segement size? How is this achieved?
Different pressures of CSF cause by transient blockages.
Where does the cephalic flexure occur?
Between the prosencephalon and the mesencephalon.
Where does the cervical flexure occur?
Between the hindbrain and the spinal cord
What does the prosencephalon divide into?
The telencephalon and the diencephalon.
What does the rhombocephalon divide into?
The metencephalon and the myencephalon.
The forebrain gives rise to which ventricles?
1 2 and 3
The midbrain gives rise to which part of the ventricular system?
The cerebral aqueduct
The hindbrain gives rise to which ventricle?
The 4th ventricle
Dorsal alar plates have what function and what are they separated by?
Sensory functions and the roof plate
The ventral basilar plates have what function and what are they separated by?
Motor function and the floor plate
What is the furrow between the basilar and alar plates called?
The sulcus limitans
What neurons in the PNS are not of neural crest origin(3)?
1. Cranial sensory neurons
2. Motor neurons which have their cell bodies in the CNS
3. Preganglionic autonomic neurons
What is the name given to cells that lie just outside the neural plate?
Placodal ectoderm cells
Cranial neural crest cells are from what level up and what are some of the things that they give rise to?
5th somite and up; skeletal elements of the branchial arches and periocular structures
Truncal neural crest cells are from what level down?
The 6th somite down.
What are neural crest cells highly prone to?
Mutations and tumors.
What is the most common neurological defect seen at birth?
Neural tube defects
What is a result of the caudal neuropore (5) not closing upon birth?
Spina bifida
What is the most common neural tube defect?
Spina bifida
What condition is usually associated with spina bifida?
Including what in your diet can cut down on the occurance of spina bifida?
Folic acid
What defect is seen as a result of anterior neuropore (2) closure?
What defect is described as having part of the brain protruding through the skull?
What is a failure of the lobes of the brain to separate?
What often is seen with holoprosencephaly?
Malfortmation of the midline structures of the face.
What are the four types of induction?
1. Binary choice
2. Graded response
3. Relayed signals
4. Reciprocal signaling
Inductive signals that allow the ectoderm to differentiate into neuroectoderm originate where?
What portion of the blastopore is the neural inducing region?
The dorsal lip of the blastopore
What chemicals are produced by the neural inducing region to promote neuroectoderm formation
1. Noggin
2. Chordin
3. Follistatin
How do the chemicals that induce neuroectoderm formation actually do that?
They antagonize BMP which is an inhibitor of neuroectoderm formation.
What family do BMPs belong to?
What is the default pathway?
Formation of neuronal tissue.
What type of cell adhesion proteins do neural plate ectoderm cells express?
N-Cadherins and N-Cam
How is the dorsal-ventral axis established? What chemical is associated which each direction of the axis?
The dorsal epidermis produces of gradient of BMP for dorsal differentiation. The notochord produces a gradient of Shh for ventral differentiation.
What mutation is specifically associated with holoprosencephaly?
What transcription factor downstream of Shh is also been linked to defects?
What set of trascription factors (large group) can also lead to defects?
Homeobox (Hox) domain TF
What signaling molecules (4) are involved in the production of the anterior/posterior axis?
1. Wnt
2. BMP
3. Retinoic acid
4. FGF
When does proliferation of cells with in the neural tube begin? End?
5 weeks; 7th month postnatally
Most neurons are produced between what days prenatally?
42 and 120
Which form first, neurons or glial cells?
At the peak level of mitosis, what is the rate of formation of neurons?
250,000 neurons/minute
Where are the cortical neurons produced?
The ventricular zone of the neural tube.
What are the two intervals of proliferation and what are their purposes?
1. Pre-neurogenic: proliferation of the cells
2. Neurogenic: cells leave and go take their place in the cortex
Where do cells form their cell to cell adhesions and undergo synaptogenesis after proliferation?
Just below the cortical plate
Why do the cells that are proliferating look like they are pseudostratified?
They are at different stages of the cell cycle.
What are the two different types of cleavage seen during cell proliferation?
1. Symmetrical 28-42
2. Asymmetrical
When do migrating cells arrive at their final destination?
Five months
What cells make the pathway for migrating neurons?
Radial glial cells
How would you describe the manner in which the cortex develops?
Inside-out manner ie the oldest cortex is the deepest
What is it called when cells migrate to a particular level and then move tangentially?
Tangential migration
Where can you find neural stem cells in adult life(2)?
Hippocampus and the sub-ventricular region of the cortex
What is the best studied molecule of migration?
What two other knock-outs have shown a result of maldevelopment of the cortex?
Apoprotein-E and VLDL receptor
What is an example of a LDL receptor that has been shown to cause defects close to holoprosencephaly in knockout models?
When does differentiation and synaptogenesis begin? End?
4 or 5 months; 6th month postnatally
What are the two types of cues that cause differentiation?
Intrinsic and extrinsic
What exactly does the differentiation process involve?
The activation of specific genes for a specific cell type.
What molecules allow synaptogenesis?
Cell adhesion molecules, neurotrophic factors (BNDF) and neurotransmitters
Are there more neurons produced than needed?
What is apoptosis? What percent of cells undergo apoptosis?
A subtractive process; 20-50%
What is responsible for the 3x of brain mass?
Increase in the density of synapes and myelination.