The brain hemisphere was fixed with 10% buffered formalin. Formalin was washed out from the tissue during an overnight tap water rinsing. Brains were dehydrated using a series of increasing ethyl alcohol concentrations (50% ethanol 3 days; 70% ethanol 4 days; 80% ethanol 3 days; 95% ethanol 4 days). The brain hemisphere was embedded in 8% celloidin [53]. During hardening, celloidin blocks were exposed to chloroform vapors for approximately 2.5 weeks, and celloidin blocks were then stored in 70% ethanol. For sectioning, the block was attached to the block holder with 10–15 ml of 8% celloidin. To fasten adhesion of the block to the holder, the block with the holder attached was immersed in 70% ethanol overnight. Serial 200-μm-thick sections were separated with filter paper and stored in 70% ethanol. For the four control and four brains of autistic subjects, alternative series of 200- and 50-μm-thick sections were preserved. To ensure the same probability of detection of changes in each case, every 200-μm-thick section, with a distance 1.2 mm, was used in this project. Sections were washed in water for 2–3 h, stained with cresyl violet (CV) and mounted with Acrytol.
