Again it is uncertain whether goblet cells discharge their contents once and for all, or whether this is a continuous process.
The mucous contents of the cells have been stained by the following methods:
Mayer's mucicarmine; Lillie's toluidine blue (Cowdry, 1943); toluidine blue
of Hempelmann (1940); periodic acid followed by Schiff's reagent (McManus,
1947), while the zymogen granules were stained either by Bensley's neutral
gentian or Bowie's ethyl-violet-Biebrich-scarlet (Cowdry, 1943).