9. Neurulation & Neural Crest Flashcards
What develops during week 1?
Formation of the inner cell mass
Days 0-7
What develops during week 2?
Formation of epiblast and hypoblast
Days 8-14
What develops during week 3?
Gastrulation
Days 15-21
What happens during days 6-10?
Implantation
What are the 3 primary germ layers?
Ectoderm
Mesoderm
Endoderm
What are the 3 features of the Primitive Streak during Gastrulation?
- Primitive knot (primitive node)
- Primitive groove
- Primitive pit
What germ layer is the Notochord derived from?
Mesoderm
What is derived from the paraxial, intermediate, and lateral plate mesoderm?
Paraxial: Somites
- Myotome (muscle)
- Sclerotome (axial skeleton)
- Dermatome (dermis)
Intermediate: Urogenital
- Kidneys
- Gonads
Lateral Plate: Somatic Connective tissue
- Blood
- Lymph
- Mesenteries
- Cardiovascular
What stimulates the formation of the neural plate and neural crest cells?
SHH (released from notochord)
What 4 structures are derived from neuroectoderm?
- Neural plate
- Neural groove
- Neural folds
- Neural tube
What does the neural tube (neuroectoderm) give rise to?
CNS (Brain and Spinal Chord)
- is a rounded hollow tube
What germ layer are neural crest cells derived from?
Ectoderm but act like mesoderm
What does surface ectoderm give rise to?
skin, hair, nails
When do the rostral and caudal neuropores close? (Primary Neurulation)
Rostral neuropore: Day 25
Caudal neuropore: Day 28
(Cervical, Thoracic, and Lumbar regions)
When does the caudal eminence form? (Secondary Neurulation)
Days 20-42
What tissues are derived from neural crest cells?
- Sensory Nerves
- Spinal ganglia
- Shwann cells
- Enteric Ganglion
- Arachnoid and pia matter
- Melanocytes (pigment in the skin)
- C-cells of the thyroid
- Chromatin cells of the medulla
- Bone and cartilage
- Teeth
Major Neurocristopathies arise from issues with what?
Neural Crest cells
What types of problems arise from defects in migration and morphogenesis of neural crest cells?
- Cleft lip/palate
- DiGeorge syndrome (thymus)
- Dental abnormalities
- Heart problems
- Eye problems
What are the 4 major congenital neural tube defects?
- Spinal bifida occulta (hidden)
- Meningocele (cyst-like sac in meninges) (may or may not have deficits)
- Meningomyelocele (herniation of meninges and spinal chord into a cyst-like sac) (motor and sensory deficits)
- Myelocele (myeloschisis) (Spinal chord cyst and spinal chord is exposed to the environment) (motor and sensory deficits)
(failure of caudal neuropore to close)
The 4 major congenital neural tube defects can be prevented with what supplement?
Folate (Vitamin B9)
What congenital neural tube defects arise from a failure of the rostral neuropore to close?
- Anencephaly
- Encephalocele (with brain tissue)
- Encephalocele (without brain tissue)
Cervical Meningocele and Frontal Encepholocele arise from what failure?
Cervical Meningocele : failure of caudal neuropore to close
Frontal Encephalocele: Failure of the rostral neuropore to close
What are the 3 developmental layers of the meninges?
Meninx Primitiva: derived from cells of the sclerotome (neural crest cells migrate and mingle) (mesoderm in origin)
Pachymeninx: dura mater (mesoderm)
Leptomeninges: arachnoid and pia mater (neural crest)
What occurs developmentally in week 4?
Folding of the embryo
