Terbium Tracing

Terbium is a small divalent cation (@ 100 d) which in solutiuon has minimal electron density. When perfused through capillaries, it binds to anionic sites in the glycocalyx on the lumenal surface of the endothelium and membranes of vesicular compartments. As a bound precipitate, terbium constitutes a highly electron-dense tracer which labels membranes and compartments to which is had access in solution. This contrasts vesicular compartments, indicating thoroughfares and provides a means whereby 3D data sets of compartment interiors can be modeled.