Ultrastructural and x-ray analytical studies on intranuclear bismuth inclusions

Parenteral administration of bismuth subnitrate produced intranuclear inclusions in the rabbit kidney tubules. In glutaraldehyde fixed material these inclusions had a homogeneous appearance but in osmicated material some of these inclusions showed a granular and fibrillar substructure. In relatively thick unstained sections prepared from unosmicated tissues, it was found that the inclusions were electron-dense, but they vanished from view when the electron beam was focussed on them. This phenomenon is thought to be due to the presence of bismuth, which is a mental with a high electrical resistance and low thermal conductivity. With the aid of electron-probe analysis the presence of bismuth was demonstrated in these inclusions and it seems possible that sulphur may be present here.