Morphogenesis of rat conjunctival goblet cells

Conjunctival flat-mount preparations stained with alcian blue and PAS were used to study the development and mucin differentiation of conjunctival goblet cells in Sprague-Dawley rats from newborn to 17 months of age. In the neonatal conjunctiva, only single goblet cells containing primarily acidic mucin (alcian-blue positive) were noted. With the increase of age, the rat conjunctival goblet cells were in clusters with heterogeneous mucin contents, which differ from the nonclustered, single goblet cells of human and rabbit conjunctiva. Topographical analysis revealed that the density and size of goblet cell clusters were highest in the forniceal zone, with gradual decrease towards the bulbar and orbital zones, and were absent in the limbal and tarsal conjunctiva in all ages. The goblet cells in the forniceal zone contained predominantly acidic mucin in all ages, except that selective loss of acidic mucin with vacuolation of the clusters was noted in the 17-month-old rats. Despite the fact that the size of the goblet cell clusters increased with age, the overall density of the clusters remained rather constant throughout the ages studied. These results indicate that each goblet cell cluster may derive from a single progenitor (stem) cell and repesents a glandular primordium, and that goblet cell development and mucin differentiation are modulated by the aging process.