Recent developments in neuropathology--electron microscopy--brain pathology

Until this meeting the observed pathology of Rett syndrome could be summarized as being a reduction of brain size, involving particularily the frontal lobes, the cauate and the midbrain, a reduced pigmentation of the substantia nigra, reduced lengths of dendrites in selected regions of the cortex, decreased neuronal size with increased neuronal packing density, reduced axonal input into the cortex, and neurochemical alterations in subplate neurons. The presentations at this session of Hand-in Hand were devoted to morphologic studies. They confirmed and further defined the selective nature of the changes in the Rett brain, cortex, and basal ganglia. They presented additional information about alterations in neuronal chemoarchitecture which support the idea that there is a developmental arrest in Rett syndrome. The degenerative changes seen in some Rett brains were not discussed. An altered morphology of the conduction system in the Rett heart was described.