VITAL STAINING OF CALCIFYING BONE AND DENTIN WITH TRYPAN BLUE

¹ Harvard School of Dental Medicine, Boston, Mass.

Freshly prepared aqueous trypan blue solution was injected intravenously into 36 white rats and 2 rhesus monkeys.

Studies on the rate at which the trypan blue was cleared from the blood indicated that appreciable amounts of this dye were still in circulation for as long as 2 weeks after the injection. Electrophoretic studies demonstrated that the trypan blue was composed of a purple fraction which migrated slowly toward the positive electrode and a stationary blue component. After injection, the purple fraction migrated with the albumin component of the serum and depressed the rate of migration of the albumin. In contrast, the blue portion of the trypan blue remained stationary.

In addition to the generalized staining of the ground substance of the mesenchymal tissues, appreciable amounts of trypan blue were deposited in the areas of the bones and dentin which were being formed while the trypan blue was in the circulatory system. In the dentin in particular, this deposition of trypan blue resulted in strong blue lines which were readily visible in ground sections.