Reexamination of granulovacuolar degeneration.

Granulovacuolar degeneration (GVD) in the hippocampal pyramidal neurons of Alzheimer-type dementia was examined. Immunohistochemical examinations showed that the majority of centrally located granules were positive for ubiquitin. Based on electron microscopic observations, morphogenesis of GVD is considered to be as follows. Slight-to-moderate amounts of electron-dense material appear in the cytoplasm at the early stage, and are then surrounded and demarcated by a two-layered membrane (probably from smooth endoplasmic reticulum). Following this some inner material is digested forming floccular and liquid-like materials, while undigested material remains as coarse electron-dense granules. Specifically, granulovacuoles are considered to be an age-related special type of autophagosome. Analytical electron microscopy disclosed that the granules in GVD contained some aluminum.