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===Development of the Brain===

===Development of the Brain===

Development of the brain begins with a series of expansions of the neural tube at the cranial end, giving rise to the internal spaces of the brain, the ventricles and aqueducts. The initial expansion of the neural tube is in the mesencephalon area, or mid brain area. This is then followed by expansions in the rhombencephalon (hind brain) and in the proencephalon (forebrain).  

Development of the brain begins with a series of expansions of the neural tube at the cranial end, giving rise to the internal spaces of the brain, the ventricles and aqueducts. The initial expansion of the neural tube is in the mesencephalon area, or mid brain area. This is then followed by expansions in the rhombencephalon (hind brain) and in the proencephalon (forebrain).  

[[Image:WIKIVETbraindifferentiation.jpg|thumb|right|300px|Brain Differentiation - © Sophie Stenner]]

[[Image:WIKIVETbraindifferentiation.jpg|thumb|right|300px|Brain Differentiation - © Sophie Stenner]]

[[File:4 week embryo brain.jpg|thumb|150px|left|Embryonic Brain Development]]

[[File:4 week embryo brain.jpg|thumb|150px|centre|Embryonic Brain Development]]

After these initial expansions, a series of further developments occurs to form some of the major landmarks in the brain. The mesencephalon narrows prior to the proencephalon resulting in the formation of the 'Foramen of Munro' and the 'Cerebral Aqueduct'. The proencephalon develops two further pouches in the cranial lateral aspect which are the foundations of the 'Lateral Ventricles' and the 'Third Ventricle'. The rhombencephalon expansion forms the 'Fourth Ventricle' and the 'Central Canal'.

After these initial expansions, a series of further developments occurs to form some of the major landmarks in the brain. The mesencephalon narrows prior to the proencephalon resulting in the formation of the 'Foramen of Munro' and the 'Cerebral Aqueduct'. The proencephalon develops two further pouches in the cranial lateral aspect which are the foundations of the 'Lateral Ventricles' and the 'Third Ventricle'. The rhombencephalon expansion forms the 'Fourth Ventricle' and the 'Central Canal'.

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In the later stages of development, the brain develops a central sulcus with defined cerebral hemispheres. The telencephalon has gyri and sulci. There is also a defined diencephalon, mid-brain, pons, cerebellum and medulla oblongata. The lumen of the neural tube remains patent within the spinal cord as a narrow central canal.

In the later stages of development, the brain develops a central sulcus with defined cerebral hemispheres. The telencephalon has gyri and sulci. There is also a defined diencephalon, mid-brain, pons, cerebellum and medulla oblongata. The lumen of the neural tube remains patent within the spinal cord as a narrow central canal.

===Formation of the Eyes===

===Formation of the Eyes===

The eyes are formed initially from expansion vesicles (called Optic Vesicles) from the lateral ventricles, as explained above. The outer portion of these vesicles then invaginates resulting in the formation of an optic cup and optic stalk.

The eyes are formed initially from expansion vesicles (called Optic Vesicles) from the lateral ventricles, as explained above. The outer portion of these vesicles then invaginates resulting in the formation of an optic cup and optic stalk.