Fig. 9. Schematic representation of mucin synthesis in conjunctival goblet cells. Mucins are synthesized in the endoplasmic reticulum, modified in the Golgi apparatus, and stored in secretory granules in the apical portion of the cell. Upon stimulus, the secretory granule membrane fuses with other secretory granule membranes and the apical membrane of the cell to release the stored mucin. Entire populations of granules in the stimulated cell are released at once. The goblet cell body then resynthesizes mucins to secrete again.