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Neurogenesis - Anatomy & Physiology (view source)
Revision as of 19:56, 29 August 2008
, 19:56, 29 August 2008→Formation of Cell Layers
#*The germinal layer is now known as the '''ventricular layer'''.
#*The germinal layer is now known as the '''ventricular layer'''.
#Cells of the intermediate layer differentiate into one of two cells:
#Cells of the intermediate layer differentiate into one of two cells:
#*Neurones - for conductance of nerve impluses.
#*[[Nervous System - PNS - Anatomy & Physiology#Nerve Fibre|Neurones]] - for conductance of nerve impluses.
#*Glia - for insulation of electrical signals. Form oligodendrocytes in the CNS, and schwann cells in the PNS.
#*Glia - for insulation of electrical signals. Form oligodendrocytes in the CNS, and [[Nervous System - PNS - Anatomy & Physiology#The Schwann Cell|schwann cells]] in the PNS.
#Glial cells surrounds the axons furthest away form the lumen of the neural tube. Because this part is myelinated, it appears ''white''. It is called the '''marginal layer'''.
#Glial cells surrounds the axons furthest away form the lumen of the neural tube. Because this part is myelinated, it appears ''white''. It is called the '''marginal layer'''.
#Axons closer to the lumen of the neural tube, which the glial cells do not surround appear ''grey''. This layer is called the '''intermediate layer'''.
#Axons closer to the lumen of the neural tube, which the glial cells do not surround appear ''grey''. This layer is called the '''intermediate layer'''.
#The ventricular layer persists, so that the spinal cord develops with these three layers.
#The ventricular layer persists, so that the [[Spinal Cord|spinal cord]] develops with these three layers.
#In the brain, futher layers are added to increase complexity. This is possible because in the anterior of the embryo, neuroblasts (cells of the ventricular layer) retain their ability to undergo mitosis after leaving the ventricular layer.
#In the [[Structure and Function|brain]], futher layers are added to increase complexity. This is possible because in the anterior of the embryo, neuroblasts (cells of the ventricular layer) retain their ability to undergo mitosis after leaving the ventricular layer.
#*This difference is achieved by increased hydrostatic forces acting on the neuroblasts.
#*This difference is achieved by increased hydrostatic forces acting on the neuroblasts.