Membrane lamellation in brain unrelated to spongiform encephalopathy

When sections from the cerebral cortex of 5 normal rats and 2 normal monkeys were stained with saturated aqueous uranyl acetate (without block staining) and examined with the electron microscope, all 7 animal brains showed abundant membrane lamellation between apposed neuronal and neuroglial processes. Such lamellations match those described by Beck et al. (1982) in the brains of kuru-inoculated monkeys in their early stages before spongiform encephalopathy has become established. The present observations question their contention that membrane lamellation is a real phenomenon and a prelude to spongiform change in kuru encephalopathy in the monkey.