True Blue (TB) Diaceturate Salt

True Blue (TB) is a fluorescent retrograde tracer used in experimental studies of the peripheral nervous system to determine the number and origin of neurons projecting to a specific area. The retrograde tracing techniques allow for detailed assessment of neuronal connections from a single population of neurons to their various targets throughout the nervous system. These techniques allow the "mapping" of connections between neurons in a particular structure (e.g. the eye) and the target neurons in the brain.

In rats, TB is effectively transported over long distances, from the spinal cord to the cerebral cortex, to produce blue fluorescent labeling of neuronal cell body cytoplasm, nucleolus, proximal dendrites and axons. When combined with Diamidino Yellow (DY), TB is effective in double labeling experiments aimed at demonstrating the existence of divergent axon collaterals.