Typical features of PMG in mature brains. a: Term baby; a festooned band of nerve cells beneath a slightly bumpy surface with normal leptomeninges. Several large intracortical vessels are seen (arrows). Little myelin is seen at this age. (Luxol fast blue and cresyl violet (LBCV)). b: 16 year old. The myelin stain (Loyez) shows a band of myelinated fibres on the cortical surface indicating disruption of the anatomy at this level as well as in the neuronal band (arrows). The leptomeninges are adherent but not markedly thickened. The deep cortical junction with the white matter is sharp.