Definition
the processes by which the three ectodermal regions are made physically distinct from one another.
Neurulation
Spina bifida is failure of closure of the ...
posterior neuropore
Ectoderm forms what three major cell lineages?
1. Ectoderm
2. Neural Crest
3. Neural Tube
Is important to indue the formation of the motor neurons.
Sonic hedgehog
When the embryo forms a neural tube what is it called?
neurula
Cells invaginate to form neural tube and separate from ectoderm
Anterior neural tube formation
Anencephaly is failure of closure of the...
anterior neuropore
What are some genes that are essential for proper neural tube formation?
Pax3, Sonic Hedgehog, Grainyhead, Tfap2, Openbrain
is important to induce the formation of sensory neurons
Bone Morphogenetic proteins
Mesenchyme cells aggregate, solid tube forms, which later becomes hollow.
Posterior neural tube formation
-The transformation from neural plate to neural tube is called primary neurulation.
-Surrounding cells direct the neural plate to invaginate and pinch off from the remaining ectoderm as a hollow tube
What is primary neurulation?
Crainiorachischisis- the failure of the entire neural tube to close over the...
entire body axis
What factors induce secondary production centers in the neural tube itself?
paracrine factors from the ectoderm (BMPs) and notochord (Shh)
Bends the neural plate at the midline
MHP- medial hinge point
-When the medullary cord fuses with the neural tube.
-Coalescing mesenchyme cells form a solid cord that then cavitates to form a hollow tube
What is secondary neurulation?
After formation will spread to a lot of areas in the body (spread to form ANS, Glial Cells of PNS, Pigment Cells, Adrenaline Cells of Adrenal Gland, most of bone and cartilage in face, and more)
Neural Crest Cells
What environmental factors play a role in NTD?
-deficiencies in cholesterol, zinc, folic acid
-diabetes, obesity, toxins, and drugs
-mechanism of effect is largely unknown
How is the neural tube polarized from dorsal to ventral?
1. Dorsal- spinal neurons receive input from sensory neurons
2. Middle- interneurons relay information between sensory and motor neurons
3. Ventral- motor neurons predominate
Two dorsolateral hinges bend the neural plate again to form the neural tube
DLHP- dorsolateral hinge point
The ultimate identity of the gene expression pattern in each set of cells is dependent on:
1. Its distance from the morphogenic signaling center (spatial/concentration)
2. The duration of the received signal (temporal)
the embryonic precursor to the central nervous system, which is made up of the brain and spinal cord.
Neural Tube
How many genes appear to be involved in proper neural tube closure?
300
What are the four stages of primary neurulation?
1. Formation of the neural plate
2. Elongation of the neural plate
3. Shaping of the plate into the neural groove
4. Closure of the neural groove into the neural tube
What factors induce secondary production centers in the neural tube itself?
paracrine factors from the ectoderm (BMPs) and notochord (Shh)
Eventually the neural tube will form what two structures?
1. Anterior- Brain
2. Posterior- Spinal cord