Answer
The forebrain or prosencephalon is one of the three primary vesicles that form by the fourth week of embryonic development.
Work Step by Step
By the fifth week of embryonic development the forebrain gives rise to the telencephalon and the diencephalon;
The following are derivatives of the telencephalon:
The two cerebral hemispheres
The lateral ventricles
The structures of the limbic system
The basal nuclei
Cerebral white matter
The following structures develop out of the diencephalon:
The thalamus
The corpora quadrigemina
The epithalamus, including the pineal gland
The hypothalamus
A part of the third ventricle
