FIGURE 4.

Development of Subependymal Nodules. (A–E) Subependymal nodules were detected at 21GW within the ventricular subventricular zone. As seen in H&E staining (A,B) small nodule (arrows) was disrupting the germ cell layer, disorganizing the radial arrangement of radial glial cells as seen with vimentin antibodies (C). Some GS + Giant cells (arrows) and dysmorphic astrocytes were already populating the tumor though they accumulate more at the periphery (D). CaBP antibodies (E) did not stain subependymal nodule cells; rather note the presence of small fusiform cells (arrows depict some of them) stained with Nissl at the periphery and at the heart of the nodule. (F,G) Images of a larger nodule taken from 25GW case. It makes clear protrusion within the ventricle (arrow in F) acquiring a rosacea configuration, with a large core of eosinophilic cells (mainly gemistocytic astrocytes) and an external ring of SF cells (G). (H–M) Subependymal nodule from 39GW case. Astrocytes (arrow in K) and Giant cells (arrow heads in K) in Subependymal nodules were immunopositive for vimentin (H,K) and glutamine synthetase + (I). Small fusiform cells can be displaced progenitors (some are indeed Ki67 immunopositive as seen (arrows) in L) but the majority were DCX + (J) suggesting that they are migrating neurons. Some dysmorphic cytomegalic (arrows) calbindin + cells can be observed on the external ring of the subependymal nodule (M). Figures were taken from 21GW (A–E), 25GW (F,G), and 39GW (H–M). Scale bars: 1 mm (B,G), 100 μm (C–E), 500 μm (H–J), and 100 μm (K–M).