part of lateral ventricle septum pellucidum BTO:0003448 BrendaTissueOBO The septum pellucidum is made up of two thin sheets of mostly glial-like elements that abut each other in the midline and have a potential space between them. Those sheets also separate the left and right lateral ventricles from each other. At the base of the sheets rostrally, however, are the septal nuclei, which are important components of the limbic system. pellucidum septum lucidum