The use of elemental iodine to enhance staining of thin sections to be viewed in the electron microscope.

A noticeable increase in contrast is observed when thin sections, stained with Reynolds lead citrate, are subsequently exposed to elemental iodine vapor for 30 seconds. There is no loss of ultrastructural detail, and there is no evidence of harmful iodine contamination of the microscope after prolonged study of such material. It is recommended that this simple procedure be used when other methods of staining have not proved adequate.