NEUR3005 – Semester 1 Be familiar with the major cellular building blocks of the central nervous system Neurons – Derived from Neural Stem cells • 100 billion neurons (but only make up only 10% of all brain cells) • Most neuronal proliferation in first 5 mths • Most neuronal differentiation 4-9 mths • Neuronal connections continue to form postnatally (after birth) Glial cells (“glue”) Function Astrocytes • Homeostatic functions (recycle glutamate) + responds to injury • Structural support of brain • Contribute to BBB Oligodendrocytes Myelination of axons for faster conduction (occurs postnatally) Microglia • Resident immune cells of CNS phagocytosis + response to injury o At rest = many mobile processes that survey area o Active = few processes to complete phagocytosis Ependymal cells • Line ventricles and choroid plexus • Produce CSF *Glial cells (except microglia) are derived from neural stem cells but differentiate later than neurons Be familiar with the development timeline of: the neural tube, primary and secondary vesicles, the ventricular system, the telencephalon, cerebral convolutions and white matter • Neurons are derived from the ectoderm (outer layer of trilaminar embryo) Formation of the neural groove (3 rd week) • Midline mesoderm releases signalling molecules which lead to thickening of the overlying ectoderm to form the neural plate • Neural plates folds inwards to form the neural groove Primary neurulation and formation of the primary vesicles (4 th week) • Neural tube closes (Day 20-26) + detaches from the ectodermal surface (the skin) o Day 24: Rostral end closes brain o Day 26: Caudal end closes spinal cord • Remaining neural crest cells form peripheral nervous system (e.g. dorsal root ganglion, glial cells) Neural tube defects • Failure of the rostral end of the neural tube to close = catastrophic developmental defect (miscarriage) • Failure of the caudal end of the neural tube to close = spina bifida
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NEUR3005 – Semester 1 · 2018. 7. 30. · • Rostral tip of the neural tube forms a thin membrane called “lamina terminalis” • Lamina terminalis is the origin of the bridge
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