Brain Development and Defects

Development of the Brain: Key Facts and Defects

• The red nucleus and substantia nigra develop from the Alar plate, with some contribution from the basal plate.
• Fibers descending from the cerebral cortex pass in front of the basal plate and form the crus cerebri.
• The cerebellum develops from the metencephalon, with the lateral margins of the developing pons forming the cerebellar plates that converge and form the two cerebellar hemispheres.
• The cerebellar plates contain outer marginal, middle mantle, and inner neuroepithelial layers, with neuroepithelial cells migrating to form the external granular layer, Purkinje cell layer, and other cell types.
• The telencephalon develops into the cerebral hemispheres, which enlarge and cover the diencephalon.
• The telencephalic vesicles of the cerebral hemispheres grow in different directions, forming different lobes of the hemisphere and extending the lateral ventricle into these lobes.
• The corpus striatum is formed from the lower part of the telencephalon, with cells in the mantle layer proliferating and migrating to form the cortex.
• The diencephalon becomes inside the cerebral hemispheres, with the superior part forming the epithalamus, the middle part forming the thalamus, and the inferior part forming the hypothalamus.
• The cerebral hemispheres grow in various directions, and by the 6th month of pregnancy, characteristic gyri and sulci are formed.
• Cranial defects affecting brain development include holoprosencephaly, schizencephaly, and ossification defects in the skull bones.
• Neural tube defects affecting the brain include excencephaly, anencephaly, and craniorachischis.
• Hydrocephalus is the accumulation of cerebrospinal fluid (CSF) in the ventricles, often due to defects in the development or obstruction of the normal route of CSF flow, while microcephaly is characterized by a smaller cranial vault and underlying brain.

Reference: Langman’s Embryology, 13th Edition, Chapter 18: Central nervous system & Chapter 20: Eye.

Development of the Brain: Key Facts and Defects

• The red nucleus and substantia nigra develop from the Alar plate, with some contribution from the basal plate.
• Fibers descending from the cerebral cortex pass in front of the basal plate and form the crus cerebri.
• The cerebellum develops from the metencephalon, with the lateral margins of the developing pons forming the cerebellar plates that converge and form the two cerebellar hemispheres.
• The cerebellar plates contain outer marginal, middle mantle, and inner neuroepithelial layers, with neuroepithelial cells migrating to form the external granular layer, Purkinje cell layer, and other cell types.
• The telencephalon develops into the cerebral hemispheres, which enlarge and cover the diencephalon.
• The telencephalic vesicles of the cerebral hemispheres grow in different directions, forming different lobes of the hemisphere and extending the lateral ventricle into these lobes.
• The corpus striatum is formed from the lower part of the telencephalon, with cells in the mantle layer proliferating and migrating to form the cortex.
• The diencephalon becomes inside the cerebral hemispheres, with the superior part forming the epithalamus, the middle part forming the thalamus, and the inferior part forming the hypothalamus.
• The cerebral hemispheres grow in various directions, and by the 6th month of pregnancy, characteristic gyri and sulci are formed.
• Cranial defects affecting brain development include holoprosencephaly, schizencephaly, and ossification defects in the skull bones.
• Neural tube defects affecting the brain include excencephaly, anencephaly, and craniorachischis.
• Hydrocephalus is the accumulation of cerebrospinal fluid (CSF) in the ventricles, often due to defects in the development or obstruction of the normal route of CSF flow, while microcephaly is characterized by a smaller cranial vault and underlying brain.

Reference: Langman’s Embryology, 13th Edition, Chapter 18: Central nervous system & Chapter 20: Eye.

Development of the Brain: Key Facts and Defects

• The red nucleus and substantia nigra develop from the Alar plate, with some contribution from the basal plate.
• Fibers descending from the cerebral cortex pass in front of the basal plate and form the crus cerebri.
• The cerebellum develops from the metencephalon, with the lateral margins of the developing pons forming the cerebellar plates that converge and form the two cerebellar hemispheres.
• The cerebellar plates contain outer marginal, middle mantle, and inner neuroepithelial layers, with neuroepithelial cells migrating to form the external granular layer, Purkinje cell layer, and other cell types.
• The telencephalon develops into the cerebral hemispheres, which enlarge and cover the diencephalon.
• The telencephalic vesicles of the cerebral hemispheres grow in different directions, forming different lobes of the hemisphere and extending the lateral ventricle into these lobes.
• The corpus striatum is formed from the lower part of the telencephalon, with cells in the mantle layer proliferating and migrating to form the cortex.
• The diencephalon becomes inside the cerebral hemispheres, with the superior part forming the epithalamus, the middle part forming the thalamus, and the inferior part forming the hypothalamus.
• The cerebral hemispheres grow in various directions, and by the 6th month of pregnancy, characteristic gyri and sulci are formed.
• Cranial defects affecting brain development include holoprosencephaly, schizencephaly, and ossification defects in the skull bones.
• Neural tube defects affecting the brain include excencephaly, anencephaly, and craniorachischis.
• Hydrocephalus is the accumulation of cerebrospinal fluid (CSF) in the ventricles, often due to defects in the development or obstruction of the normal route of CSF flow, while microcephaly is characterized by a smaller cranial vault and underlying brain.

Reference: Langman’s Embryology, 13th Edition, Chapter 18: Central nervous system & Chapter 20: Eye.