Biotinylated dextran amines (BDA) are organic compounds used as anterograde

Anterograde tracing

In neuroscience, anterograde tracing is a research method which is used to trace axonal projections from their source In neuroscience, anterograde tracing is a research method which is used to trace axonal projections from their source In neuroscience, anterograde tracing is a research method which...

 and retrograde

Retrograde tracing

Retrograde tracing is a research method which is used in neuroscience to trace neural connections from their point of termination to their source . The opposite technique is anterograde tracing, which is used to trace neural connections from their source to their point of termination...

 neuroanatomical tracers

Histochemical tracer

A histochemical tracer is a compound used to reveal the location of cells and track neuronal projections. A neuronal tracer may be retrograde, anterograde, or work in both directions...

. They can be used for labeling the source as well as the point of termination of neural connections

Neuron

A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

 and therefore to study neural pathway

Neural pathway

A neural pathway, neural tract, or neural face, connects one part of the nervous system with another and usually consists of bundles of elongated, myelin-insulated neurons, known collectively as white matter...

s.

BDA is delivered into the nervous system by iontophoretic

Iontophoresis

Iontophoresis is a technique using a small electric charge to deliver a medicine or other chemical through the skin. It is basically an injection without the needle...

 or pressure injection and visualized with an avidin-biotinylated Horseradish peroxidase

Horseradish peroxidase

The enzyme horseradish peroxidase , found in horseradish, is used extensively in biochemistry applications primarily for its ability to amplify a weak signal and increase detectability of a target molecule.-Applications:...

 procedure, followed by a standard or metal-enhanced diaminobenzidine

3,3'-Diaminobenzidine

3,3'-Diaminobenzidine is an organic compound. This derivative of benzidine is a precursor to polybenzimidazole fiber. As its water-soluble tetrahydrochloride, it has been used in immunohistochemical staining of nucleic acids and proteins.-Preparation:...

 (DAB) reaction. Samples can then be analyzed by optical microscopy as well as by electron microscopy.

High molecular weight BDA (10 kDa) yields sensitive and detailed labeling of axons and terminals, while low molecular weight BDA (3 kDa) yields sensitive and detailed retrograde labeling of neuronal cell bodies .