Anomalies of development of the cerebral cortex

See also: Cortex (homonymy)

The means of detection of the anomalies concerning the development of the cerebral cortex made enormous progress since the appearance of the medical imagery of the brain. Several studies reveal that nearly 25% of the children reached of refractory epilepsies are in connection with anomalies of development of the cerebral cortex.

Embryology

With the difference of much of another cells during embryogenesis, the cerebral cells of the cortex are not different on the level from the cerebral cortex but remotely, it will have to thus migrate towards the cerebral Cortex.

The two places of formation of the neurons are the walls of the Third ventricle and the side ventricles.

During the seventh week of gestation, a proliferation of neurons occurs in the wall of the ventricles side. In this zone of proliferation or germinal zone or matrix germinal, the original cells become Neuron S or cells gliales intended to become the future brain. Some of these cells will remain on the spot or it will continue to proliferate, while others will migrate to form the future cortex. This migration starts as from the eighth week of gestation, which is remarkable in this process it is the correspondence between each zone of the germinal matrix and the cerebral cortex. The displacement of the neurons is done by a simple mechanism: cellular elongation and migration of the core towards the opposite end of the cell at the germinal zone. Then the part in contact with the ventricle side in retracts. The development of the brain and the increase in the distances require mechanisms of migration more sophisticated thanks to the cells gliales which by emitting fibrillary prolongations direct the migration. The cells gliales provide moreover the metabolites necessary to the migration. The cellular organization of the cortex is made depth with the periphery: The polymorphic layer being formed the first.

Classifications

According to the embryology, one can classify schématiqueemnt the anomalies of development of the cerebral cortex in three categories:
  • Malformations in connection with an anomaly of the proliferation of the neurons and cells gliales
  • Malformations in connection with an anomaly of the proliferation of the neurons
  • Malformations in connection with an anomaly of the cortical organization of the neurons

Sources

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