In spite of the broad spectrum of clinical manifestations and striking inter-individual differences, studies of thousands of children have resulted in establishing the clinical diagnostic criteria of pervasive developmental disorder [1]; however, corresponding neuropathological diagnostic criteria do not exist. One of the reasons for the disproportionate progress in clinical and neuropathological studies is the limited tissue resources available for postmortem studies. Between 1980 and 2003, only 58 brains of individuals with autism were examined [85]. Due to the diversity of research aims, of protocols for tissue preservation and of methods of sampling and examination, and the small number of brains examined in an individual project, the pattern of neuropathological changes emerging from these studies remains incomplete and inconsistent.
