Radioautographic study of glycoprotein synthesis and migration in the major sublingual gland of the Mongolian gerbil (Meriones unguiculatus).

Intracellular glycoprotein synthesis and migration in the major sublingual gland of the Mongolian gerbil were studied with light-microscopic radioautography, using L-4, 5-[3H]-leucine, D-1-[3H]-glucose and N-[3H]-acetyl-D-mannosamine as precursors. The time elapsed from the beginning of the synthesis of the secretion products to their release was longer in the mucous acinar cells than in any other exocrine cell investigated until now. A slow addition of the terminal sugars (especially sialic acid) to the glycoprotein molecule and a prolonged storage of the glycoproteins in the apical granules were assumed to be the reasons for this delay in schedule. The secretion in the serous demilune cells was much faster than in the mucous acinar cells. The lack of uptake of labelled mannosamine showed that the demilunes are likely to produce substances different from those of the mucous acinar cells, presumably a protein-rich material with a high turnover.