Aberrant-type cysts. A comparison between luminal (a) and dural (b) cyst wall in a case where the SEM architecture of the dural side was particularly complex. Luminal cells (a) form a smooth surface with intermediate density of microvilli. Note elongated strands of cellular irregularities giving an uneven webbed dural surface (b). In comparison, (c) depicts an isolated sample where connective tissue filament bundles were exposed in the absence of covering cells on the luminal surface.