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Neurogenesis - Anatomy & Physiology (view source)
Revision as of 12:16, 9 November 2010
, 12:16, 9 November 2010no edit summary
#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|spinal cord]] develops with these three layers.
#The ventricular layer persists, so that the spinal cord develops with these three layers.
#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.
#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.
#*This difference is achieved by increased hydrostatic forces acting on the neuroblasts.
#*This difference is achieved by increased hydrostatic forces acting on the neuroblasts.
*Sensory neurones enter the central nervous system (CNS) through the '''dorsal root'''.
*Sensory neurones enter the central nervous system (CNS) through the '''dorsal root'''.
**Sensory neurones have their cell bodies in dorsal root ganglia (DRG). DRG are evenly spaced along the [[Spinal Cord|spinal cord]].
**Sensory neurones have their cell bodies in dorsal root ganglia (DRG). DRG are evenly spaced along the spinal cord.
*Response to the stimulus is mediated by a single motor neurone.
*Response to the stimulus is mediated by a single motor neurone.
**Somatic motor neurones have their cell bodies in the CNS. They leave the CNS by the '''ventral root'''.
**Somatic motor neurones have their cell bodies in the CNS. They leave the CNS by the '''ventral root'''.