Histologic neuropathology. (A, B) Polymicrogyria-like cortical dysgenesis stained by immunohistochemistry for (A) N52 and (B) MAP1B. Note “festooned” supragranular layers in the patient’s superior frontal gyrus (SFG) and adjacent dorsolateral frontal cortex (superior up, lateral left). The cingulate cortex (Cg) was unaffected, except in the depth of the cingulate sulcus. The corpus callosum (CC) was hypoplastic. (C-E) Lamination of normal, age-matched control cortex demonstrated by (C) N52, (D) MAP1B, and (E) cresyl violet (Nissl) stains. (F, G) Polymicrogyria -like cortical dysgenesis seen at higher magnification (boxed areas from A, B). (H-K) Two-color, double-label immunofluorescence detection of N52 (green) and calretinin (red) in control (H, J) and patient (I, K) cerebral cortex. Low magnification views (H, I) show dot plots of immunolabeled cells. In patient cortex, the number and size of N52+ neurons appeared smaller, but the relative positions of N52+ and calretinin + neurons were unaltered. (L) Multiple synaptophysin-immunoreactive periventricular nodular heterotopia and small irregular heterotopia were identified in occipitotemporal regions adjacent to the lateral ventricle (LV). (M) Periventricular heterotopia exhibited N52 (green) and calretinin (red) immunoreactivity, represented in dot plots. Insets (a, b) show higher magnification photomicrographs. (N) The inferior olivary nuclei appeared slightly simplified with reduced convolutions. (O) The central canal of the spinal cord showed mild hydromyelia with a cross-shaped dilatation in lower thoracic and upper lumbar levels. Note also pallor of anterior and lateral funiculi. Scale bars: (in A) A, B, 5 mm; (in C) C-E, 1 mm; (in F) F, G, 1 mm; (in H) H, I, 500 μm; (in J) J, K, 250 μm; L, 2 mm; M, 500 μm; N, 2 mm; O, 2 mm.