Second, the fact that the photographic images of brain slices, but not the histological preparations, revealed smaller hippocampal volume in schizophrenia is intriguing. The histologically defined volume estimates included only the cell-containing regions, whereas the volume estimates derived from photographic images included adjacent tissue as well. Ms. Walker et al. interpreted this as evidence for changes of the parahippocampal gyrus to strengthen their argument that isocortical but not allocortical structures of the medial temporal lobe are abnormal in schizophrenia. However, an alternative explanation seems more likely: the tissue adjacent to the cell-containing regions that is reduced in volume in schizophrenia is the hippocampal white matter, which cannot be distinguished easily from hippocampal gray matter on unstained brain slices. A decrease of white but not gray matter volume and normal total number of all subpopulations of hippocampal neurons is exactly the finding of the only other stereological study of the hippocampus in schizophrenia (6).