Aclar

In one Type IIb FCD case, part of the specimen after 4% PFA fixation was cut at serial 50 μm‐thick sections using a vibratome (VT1000S, Leica Microsystems, Heidelberg, Germany) and processed for pre‐embedding immunohistochemistry. Vibratome sections underwent mild ethanol pretreatment to increase the penetration of immunoreagents, and were processed with the immunoperoxidase protocol to detect Iba1 immunoreactivity (1:1000 in blocking solution). The immunoreacted section was then postfixed for 10 min in 2.5% glutaraldehyde in PB, washed and postfixed for 1 h in 1% OsO₄, dehydrated, cleared in propylene oxide, flat‐embedded in Epon‐Spurr between acetate sheets (Aclar; Ted Pella, Redding, California) and polymerized at 60° for 36 h. After polymerization, embedded sections were examined under a dissecting microscope and small gray matter areas inside the dysplastic lesion were excised with razor blades and glued to cured resin blocks. Semithin (1‐μm thick) sections were then cut with a ultramicrotome (Reichert–Jung Ultracut E, Germany) and collected on glass slides with toluidine blue counterstaining for light microscopic inspection to control the histopathological features. In areas of interest, ultrathin sections (80 nm) were then obtained, counterstained with lead citrate and samarium and gadolinium triacetate and examined with a Tecnai™ Spirit transmission electron microscope.