abnormal neural tube mantle layer morphology abnormal spinal cord alar plate morphology MP:0009692 MPheno.ontology abnormal spinal cord alar column morphology abnormal spinal cord alar lamina morphology any structural anomaly of the region of the mantle layer of the neural tube that lies dorsal to the sulcus limitans and contains primarily sensory neurons and interneurons involved in communication of sensory impulses; the alar plate develops into the dorsal horn in the grey matter of the spinal cord