The cerebral hemispheres develop from the telencephalon, which consists of a median part and two lateral diverticula. These diverticula are the primordia of the hemispheres. As the hemispheres expand, their walls thicken and cover other brain structures. Various structures develop within the hemispheres, including the corpus striatum, hippocampus, internal and external capsules, and cerebral cortex. The lateral ventricles develop from cavities within the telencephalon diverticula.