Fig. 1

Main neuropathological hallmarks of hydrocephalus linked to CCDC88C pathogenic variants. a Coronal section through the mesencephalon reveals AS atresia in the first case (thick arrows) associated with small- and medium-sized channels lined by ependymal cells (thin arrows) [H&E, OM × 100)]. b By comparison with a normal aqueduct of Sylvius [H&E, OM × 100)]. c Identical lesions (arrow) observed in the second case at the level of the central canal of the medulla the AS [H&E, OM × 25]. d With, at higher magnification, presence of several small ependymal channels [H&E, OM × 100]. e Periventricular nodular heterotopias of various size (thick arrows) [H&E, OM × 25]. f With at higher magnification, a lower cell density [H&E, OM × 100)]. H&E: Hematoxylin and eosin stain; OM: original magnification; P: pyramids