Neural development

Option A1

Essential idea: Modification of neurons starts in the earliest stages of embryogenesis and continues to the final years of life.


A.1.U1 The neural tube of embryonic chordates is formed by in folding of ectoderm followed by elongation of the tube

Formation of the neural tube of embryonic chordates

A.1.U2 Neurons are initially produced by differentiation in the neural tube

Neurons differentiated from the neural tube

A.1.U3 Immature neurons migrate to a final location

Migration of neural tube and neural crest cells
Final locations of immature neural tube and neural crest cells

A.1.U4 An axon grows from each immature neurons in response to chemical stimuli

Mechanisms of axon growth in immature neurons

A.1.U5 Some axons extend beyond the neural tube to reach other parts of the body

Neurons differentiated from the neural tube

A.1.U6 A developing neuron forms multiple synapses

Synapase generation in neurons

A.1.U7 Synapses that are not used do not persist

Synaptic pruning explained

A.1.U8 Neural pruning involves the loss of unused neurons

Death of neurons

A.1.U9 The plasticity of the nervous system allows it to change with experience

Brain plasticity and changing environments


A.1.A1 Incomplete closure of the embryonic neural tube can cause spina bifida

Formation of spina bifida

A.1.A2 Events such as strokes may promote reorganization of brain function

What conclusion regarding the effect of post-rehabilitation of stroke survivor can you make using the fMRI images below?

Place your mouse pointer on the images to view the conclusion

Conclusion for effect of stroke post-rehabilitation


A.1.S1 Annotation of a diagram of embryonic tissues in Xenopus, used as an animal model, during neurulation

Diagram of Xenopus embryonic tissues

Can you identify the Xenopus embryonic tissues in the electron micrograph below

Place your mouse pointer on ECG to view tissue labels

Identifying xenopus embryonic tissue
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