In the presence of calcium, rat gastric mucus granules aggregate and possibly fuse.
Crude rat gastric lining cytosol (centrifuged at 20,000g)
Rat gastric lining cytosol with calcium, showing aggregation of small bodies remaining in crude cytosol
Rat gastric mucus granules in the absence of calcium
Rat gastric mucus granules in the presence of calcium. Note the near-absence of free granules in the cytosol around granule aggregates.