The distribution of indium in the central and peripheral nervous system of the young rat.

A subtoxic quantity of radioactive 111indium and stable indium was injected once into young rats. Subsequently pairs of these rats were killed at intervals of 15 minutes to 3 days after the injection. Tissues from the central (CNS) and peripheral nervous system (PNS) and blood were removed from each rat and the amount of 111indium was measured in the tissues. Cryostat sections of the cerebrum, cerebellum, spinal cord, sciatic nerve, a blood smear and a kidney control from each rat were examined with an analytical ion microscope (secondary ion mass spectrometry analysis) and the presence of 113 and 115 indium was localized in the tissues. These observations show that indium penetrates all neural tissues and that the brain resists the entry of indium - a very toxic element - much more effectively than the sciatic nerve.