vFollowing acute tetraethyl lead intoxication in rabbits classic neurofibrillary tangles develop. As
studied by electron microscopy, such tangles develop in
hydropic degenerating neurons and consist primarily of
bundles of 200 A diameter smooth tubules of enormous
length. In two of 16 animals a few twisted tubules
(periodicity of 800 A) also could be found. The significance of
these lead-induced twisted tubules, so characteristic
of Alzheimer's
pre-senile dementia in man, is discussed.