The layer of glia and differentiating neurons that forms as a second layer around the germinal neuroepithium; as this develops it comes to lie between the ventricular and marginal layers and includes the basal and alar plates. Develops into neurons and glia forming a gray matter layer. [ http://www.ncbi.nlm.nih.gov/books/NBK10047 MP:0009690 ]
Synonyms: neural tube intermediate zone