Lesson 1 - Development Of CNS Flashcards
What does (a) and (b) develop into?
(a) neuroepithelium
(b) neural crest
(a) CNS
(b) PNS
What cells arise from the differentiation of the neuroepithelium?
Neuroblasts - all neurons with cell bodies in the CNS
Glioblasts - astrocytes and oligodendrocytes
Ependymal cells - lining ventricles and central canal
What cells arise from the differentiation of neural crest cells?
Sensory neurons of the dorsal root ganglia
Postganglionic autonomic neurons
Schwann cells
Non-neuronal derivatives - like melanocytes
What is the proliferation of the neuroepithelium like?
Actively dividing from inside to outside
Massive proliferation
Differentiation of neuroepithelium
Differentiates into neuroblasts and ependymal layer. Neuroblasts cell bodies form grey matter. Axons form white matter.
What are the layers of the neural tube?
Neural crest Roof plate Ependymal layer Grey matter White matter Floor plate
How does the neural tube develop
The neural plate lift upward, forming the neural folds. The centre of the neural plate remains grounded which allows a neural groove to form, that serves as the boundary between the right and left sides of the brain. The neural folds pinch in towards the midline and fuse together to form the neural tube.
How do neuroepithelial cells differentiate?
Signalling molecules are secreted by surrounding tissues, interacts with receptors on neuroblasts
This controls migration and axonal growth by attraction and repulsion
What factors do differentiation of neuroepithelium depend on?
Concentration gradient and timing
What do these parts in the developing spinal cord develop into?
A) neural crest cells
B) neurons in the alar plate (interneurons)
C) neurons in the basal plate (motor and interneurons)
A) sensory neurons in the dorsal root ganglion
B) interneurons in the dorsal horn
C) motor and interneurons in the ventral horn
Describe the developing brain at 4 -> 5 -> 8 weeks
Prosencephalon->telencephalon-> LV
->diencephalon ->V III
Mesencephalon ->mid brain->aqueduct
Rhombencephalon->pons -> developing cerebellum
->medulla
What are the three flexures in the developing brain and what do they become
Cephalic flexure - brain
Pontine flexure - pons
Cervical - spinal cord
What does normal development of the brain depend on?
co-ordination of several complex processes - proliferation, differentiation, migration, axon growth, synapse formation
What kind of factors can affect normal development?
Genetic mutation Environmental factors - mother’s lifestyle - diet - teratogens
Name some neural tube defects
Craniorachischisis Anencephaly Encephalocele Iniencephaly Spina bifida occulta Closed spinal dysraphism Meningocele Myelomeningocele
What is craniorachischisis
Completely open brain and spinal cord
What is anencephaly
Open brain and lack of skull vault
What is encepalocele
Herniation of the meninges and brain
What is iniencephaly
Occipital skull and spine defects with extreme retroflexion of the head
What is spina bifida occulta
Closed asymptomatic neural tube disorder in which some of the vertebrae are not completely closed
What is closed spinal dysraphism
Deficiency of at least two vertebral arches, sometimes covered with a lipoma
What is a meningocele
Protrusion of the meninges, filled with CSF, through a defect in the skull or spine
What is a myelomeningocele
Open spinal cord with a meningeal cyst
