Myelencephalon gives rise to the medulla oblongata. Its lateral walls rotate around the longitudinal axis, so that the alar and basal plates separated by the sulcus limitans can be clearly distinguished. The basal plate contains motor nuclei, while sensory nuclei are in alar plate. The roof plate of the myelencephalon forms the tela choroidea (ependymal roof covered by pia mater), which invaginates and differentiates into the plexus choroideus (site of the production of the cerebrospinal fluid). The cavity of the rostral part of the myelencephalon becomes the caudal part of the fourth ventricle.