Radioautographic analysis of [3H]-fucose utilization by mouse odontoblasts with emphasis on intracytoplasmic and plasma membrane glycoproteins.

[3H]-fucose utilization by odontoblasts was studied by light and electron microscopic radioautography. At 10 min after injection, fucose label was concentrated in the Golgi area. By 20-30 min, there was a progressive decline in Golgi labelling with label present at the plasma membrane, terminal web, odontoblast process and predentine matrix. At 4 h, the predentine and the predentine-dentine junction were heavily labelled. At the ultrastructural level, Golgi labelling at 10 min was mostly localized to cisternal elements and at 20 and 30 min secretory granules and dense bodies were also labelled. Most of the silver grains observed in the terminal web were associated with microfilaments near the plasma membrane. In the predentine, the matrix itself accounted for 23.0 per cent of the label at 4 h and the plasma membrane of the odontoblast process accounted for 19 per cent. The results indicate that odontoblasts, in addition to secreting glycoproteins into the dentinal matrix, also continuously manufacture glycoproteins for incorporation into the cell surface, the lysosomal system and the terminal web.