the cerebrum develops from a vesicle of the embryonic brain called the
telencephalon. 1. one of the two divisions of the prosencephalon, consisting of the cerebrum. 2. the anterior of the two vesicles formed by specialization of the prosencephalon in embryonic development. Called also endbrain. adj., adj telencephalÂ´ic.elencephalon. 1. one of the two divisions of the prosencephalon, composing the cerebrum (q.v.). 2. the anterior of the two vesicles formed by specialization of the prosencephalon in embryonic development; from it the cerebral hemispheres are derived.telencephalÂ´ic.