Lecture 17 Nervous System Dev.II Flashcards
Topographical arrangement of myelecephalon is almost identical to spinal cord, what is the major change?
Pronounced expansion of the roof plate to form the thin roof over the fourth ventricle
What genes are responsible for differentiation of specific nuclei in myelencephalon?
Hox
What do the mutations weaver and reeler have to do with building of cerebral cortex?
Weaver is a mutation in a mouse with specific behavioral defects related to abnormal function of cerebellum-defect in radial glial cells.
Reeler is abnormal behaavor in absence of nrmal cortical layering.
What is the relation of reelin to reeler?
Reelin is the defective extracellular protein found in the mutant reeler
Relate columnar radial units to organization of cerebral cortex.
Radial units are the six layers of grey matter that form the cerebrum. They migrate up radial glial cells laying down each layer of neurons from largest to smallest.
Cerebellum forms in region of rhombic lips. Rhombic lips are product of what inductive interaction?
Roof plate and neural tube via BMP signaling
What are major derivatives of metencephalon?
Pons (basal plate) and Cerebellum (alar plate)
Depends on FGF-8 from isthmic organizer
Review the migration of cells that form the cortex in cerebellar primordium.
Granule cells migrate anteriorly along dorsal region of rhombomere 1
Granule cells migrate interiorly through Purkinjie layer
Purkinje cells migrate radially through granule cells
What are superior cerebellar peduncles
massive fiber bundles between cerebellum and mesencephalon
What are major derivatives of the alar plates of the mesencephalon?
Tectum (corpora quadrigemina): Superior and inferior colliculi
Where is Otx-2 located and how is it related to shh?
Confines Shh to the basal part of midbrain
Where do cerebral peduncles form and function?
Ventrolateral region of the mesencephalon and they carry fibers between the cerebral hemispheres and the spinal cord
What are major derivatives of the diencephalon?
epithalamus, thalamus, and hypothalamus
What are the three patterning centers in the forebrain and their signaling molecules?
Rostral patterning center (FGF-8)
Dorsal patterning center (BMP’s and Wnt’s)
Ventral patterning center (Shh)
Describe formation of corpus striatum and corpus callosum.
The base of each telencephalic vesicle thickens to form corpus striatum, dorsal to thalamus it becomes C shaped. Many fiber tracts converge here.
Corpus Callosum is the third commissure to shape in the lamina terminalis and most important connection btw right and left halves. Complete by 115 days. EMX2 mutation leads to split brain (schizencephaly)
Arnold-Chiari malformation and relation to hydrocephalus?
Specific malformation leading to Hydrocephalus, where parts of cerebellum herniate into foramen magnum and prevent escape of CSF from skull.
What is rhinecephalon?
There is a decrease in the prominence of it as the cerebrum grows. Oldest and most primitive area in the telencephalon, heavily involved in smell.
What is archicortex?
Rhinencephalon the oldest and most primitive component of the telencephalon
What is neocortex?
Morphologically dominant cerebral hemispheres. As development occurs neocortex takes over as the component of most of brain mass.
Relate cranial nerves to pharyngeal pouches and modalities?
CN V, VII, IX, and X and VIII suppply pharynegeal arches
Why is CN II not true nerve?
CN I and II are not considered true because they are extensions of brain tracts
Origin of cranial nerve ganglia?
Motor nerves developed from ventral roots and sensory come from neural crest and ectodermal placodes.
Define Rachischisis.
Closure defect of spinal cord
brain closure defect is cranioschisis
What substance when present in amniotic fluid in elevated amounts can be diagnostic of closure defects?
a-fetoprotein
Order closure defects from least to most serious.
Spina Bifida Occulata: spinal cord meninges in place but neural arch incomplete, tuft of hair over defect
Meningocele: missing duramater arachnoid bulges beneath skin
Myelomeningocele: spinal cord bulges into subarachnoid space
Raschischisis: failure of neural folds to close
Functional regions in spinal cord and brain:
Alar Plate (Afferent): general somatic, special visceral afferent, General visceral afferent
Basal Plate (Efferent): General visceral efferent Special visceral efferent General somatic efferent
Myelencephalon derivitives?
Medulla Oblongata
