生物素-葡聚糖，Biotin-dextran；mol wt 10,000, Lysine-fixable

Biotin-dextran is used in tissue staining to prepare neurons for detection by avidin-conjugated detection systems. It is taken up by neuronal processes and transported bi-directionally. It infiltrates axon boutons in the anterograde direction and dendritic processes in the retrograde direction.[1] Staining can be observed in fixed and sectioned tissue from two days to two weeks after biotin-dextran is injected into the brain or spinal cord. It can also be applied to cut nerve tracts.[2] Biotinylated neurons are detected by either light or electron microscopy following incubation with avidin-horseradish peroxidase conjugate and the electron-dense substrate 3,3′-diaminobenzidine (DAB).[3]