Defective Proliferation. A decrease in neuronal number may lead to microcephaly (microencephaly vera), whereas an increase may result in megalencephaly. Prenatal influences, including familial factors, are paramount in each abnormality….
The earliest-born neurons of the cortex itself migrate through the preplate, splitting it into the marginal zone and subplate, thus constituting layer 6 of the cortex. Each successive cortical neuron…
Once these interactions have progressed, the prosencephalic vesicle expands so that there are two telencephalic vesicles. Based on their proximity to anteromedial and anterior sonic hedgehog and FGF signals or…
Brachial birth palsy is believed to be secondary to a stretching of the plexus by traction, with the nerve roots being anchored by the spinal column and cord. In less…
Another type of cell, which is derived from both the neural crest and the wall of the neural tube and which participates in covering the neurons of the PNS, is…
Oligodendrocytes in the CNS and Schwann cells in the PNS form myelin sheaths by similar processes. In an action similar to the continuous wrapping of a bolt of cloth, the…
The direction of growth chosen by axons from different neuron classes must be exquisitely regulated to ensure proper connectivity within spinal cord circuits. Thus motor neurons, whose axons are the…
The neural stem cells in the spinal cord and hindbrain can be divided into four broad classes: motor neurons and related interneuron progenitors, sensory relay neurons and related interneuron progenitors,…
Neural stem cells that give rise to mature brain neurons and glia, with few exceptions, comprise a layer of cells that lines the ventricular space of the neural tube throughout…
Many children have CP related to birth trauma (see Plates 1-2 and 1-3) more attributed to hypoxicischemic encephalopathy (HIE). Low oxygen combined with impaired blood flow is particularly damaging. After…
