Improvement of cobalt-transport in axons by complexing agents

The use of the cobalt technique is limited by the fact that cobaltous ions travel within axons for a shorter distance than do other intracellular markers. In the present experiments different organic cobaltous complexes were tested in the rat's sciatic nerve. Cobaltous complexes containing ornithine, threonine, lysine or Girard's reagent travelled two or three times further than did the cobaltous ions alone. Using the lysine complex in the frog's visual system, very fine terminals were observed which have never been demonstrated with other techniques. The possible use of other metal complexes as intracellular markers are also discussed.