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Describe the process of neurulation.
Cells invaginate through primitive pit and migrate towards buccopharyngeal membrane.
What do notochrodal cell migrating forward forming a shild shape overlying structure give rise do?
What does neuroectoderm give rise to?
CNS and retina
How does the neural tube form?
Neural folds come together in midline over neural groove and fuse. Neuropore then zips up cranially and caudally.
What does the neuropore communicate with?
As neural folds differentiate into as they approach midline, differentiate, and detach laterally?
neural crest cells
What does the neural crest give rise to?
- 1) Melanocytes
- 2) Cartilage of bones in head from pharyngeal arches
- 3) C cells of thyroid
- 4) Aorticopulmonary septum
- 5) Odontoblasts
- 6) Adrenal Medulla
- 7) Sensory and Motor Ganglia
- 8) Schwann Cells
What does the mangle layer of the spinal cord form from?
Neuroepithelial cells that differentiate into neuroblasts
What does the marginal layer of the spinal cord come from?
Neuroblasts that differentiate into neurons and processes that extend into marginal layer
What forms the ventricular layer of the spinal cord?
Neuropithelial cells that do not differentiate
What divides the mantle zone of the spinal cord into two latyers? What does this separate?
- Sulcus limitans (Alar and Basal plate)
- Alar = sensory
- Basao = motor
- Separates snesory and motor functions
What layers in spinal cord are between white matter? Grey matter?
- White - Marginal layer
- Grey - Mantle layer
What forms the wall of the thrird ventricle in the brain?
Thalamus and hypothalamus
Describe the flow of CSF.
CSF is produces in lateral ventricle (choroid plexus) --> third ventricle --> fourth ventricle --> subarachnoid space --> reabsorbed through acahnoid villi
What are the three primary vesicles the nerual tube dilates into?
- Forebrain (proscencesphalon)
- Midbrain (mesencephalon)
- Hindbrain (rhombencephalon)
What does the forebrain (prosencesphalon) give rise to?
Telencephalon and Diencephalon
What does telencephalon give rise to?
What does diencephalon give rise to?
What is the lateral wall of the third ventricle?
What dilation gives rise to midbrain?
What dilation gives rise to pons and cerebellum?
What dilation gives rise to medulla?
What is the arrangement of the alar and basal plate in the floor of the 4th ventricle ?
- Alar is lateral to basal
- (Remember - alar is sensory and basal is motor)
What does neurectoderm give rise to?
- 1) CNS, retina, CN II
- 2) Neurohypophysis
- 3) Astrocytes, Oligodendrocytes
What does the musculoskeletal system derive from mainly?
What does proliferation of mesoderm near the notochord produce?
- Paraxial mesoderm.
- The remaining mesoderm is called lateral plate.
What is between lateral plate and paraxial mesoderm?
What does paraxial mesoderm form?
What three regions does each somite have?
What are less well organized regions of paraxial mesoderm cranially called?
What is a sclerotome made of?
Medial and ventral cells that migrate away and head toward notochord that becomes bone and cartilage of vertebral column.
How many sclerotomes make up a vertebral body?
- Caudal and cranial portion of different sclerotomes fuse to form v. bodies.
What does the remnant of the notochord form?
Nucleus pulposus in intervertebral disk
What germ layer do the bones of the face form from?
Neural crest forms sphenoid bone, squamos portion of temporal bone, frontal, madible, etc.
What does the rest of the cranial vault form from?
What does a dermatome form?
Dermis of skin
What does a myotome form?
muscles of the region and retain segmental innervation
What are some clinical signs of spina bifida?
- Tuft of hair covering lesion
- Increased AFB and AchEsterase
What happens when the neural tube fails to close caudally?
- Spina bifida (can be spina bifida occulta - no fusion of vertebra)
- Spina bifida meningocele (with meninges protruding)
- Spina bifida meningomyelocele (with spinal cord and meninges)
What can meningomyelocele lead to?
Arnold Chiaria malformation
What is Rachiscisis?
failure of spinal cord to form
What happens when the neuropore fails to close cranially?
What causes clinical presentation of anencephaly?
- Exposes brain to amniotic fluid which destroys brain
- Increased amnion fluid
- Increased AFB
What vies rise to the intrinsic muscles of the back?
What does hypomere give rise to?
muscle with thoracic, lateral and medial abdominal wall (muscles of trunk), some of hypomere forms limb muscles
What vies rise to limb bones?
What sends messages into underlying mesenchyme for limb differentiation?
What are the first bones of the limb to develop?
Forearm, then hands, them humerus
Where did parietal mesoderm come from?
lateral plate mesoderm
What forms the digits of the hand? What does a failure of this process cause?
- Apoptosis (programmed cell death)
What is it called when there is a complete abscence of limbs? Partial?
- Complete - amelia
- Partial - melomelia
- (thalidomide caused this)
What does parietal lateral plate mesoderm give rise to?
serous lining of peritoneal, pericardial, and pleural membranes
What does visceral lateral plate mesoderm give rise to?
cardiac and smooth muscle
Describe the formation of the skeletal system.
- Skeletal system is ALL from mesoderm
- Sclerotome, Somite = bones of axial skeleton, cranial vault
- Somatic layer of lateral plate mesoderm = bones of shoulder, pelvic girdle, and limbs
- Neural crest = bones of face
* The posterior neuropore provides a communication between what two spaces?
The developing neural tube and the amnion
* Cells of the adrenal medulla are derived from what?
neural crest cells
* The vertebrae are derived from segmental _______.
* What part of the brain's ventricular system is derived from the diencephalon?
* The membrane lining the abdominal cavity is derived from what division of mesoderm?
* The sulcus limitans divides the developing central nervous system into what two major functional area?
sensory and motor