part of part of bounding layer of adjacent_to neural tube neural tube lumen germinal neuroepithelium As the cells adjacent to the lumen continue to divide, the migrating cells form a second layer around the original neural tube. This layer becomes progressively thicker as more cells are added to it from the germinal neuroepithelium. This new layer is called the mantle (or intermediate) zone, and the germinal epithelium is now called the ventricular zone (and, later, the ependyma)[NCBIBook:NBK10047] The single layer of epithelial cells that lines the early neural tube and develops into the nervous system and into the neural crest cells UBERON:0004022 germinal neuroepithelial layer germinal neuroepithelium original neural tube uberon embryonic tissue ecto-epithelium proliferating neuroepithelium