Early growth of the cranial end of the neural tube, the prosencephalon, is highlighted by the expansion of the right and left cerebral hemispheres, as shown both in the three dimensional and longitudinal images. This expansion is the visible manifestation of a split of the prosencephalon into two regions; the telencephalon, which is the cranial most portion, including the cerebral hemispheres that grow from that region, and the diencephalon, which will give rise to the thalamus, hypothalamus and epithalamus.

Also note the division of the rhombencephalon into two regions; the metencephalon, which will form the pons and cerebellum, and the myelencephalon, which will develop into the medulla.