Epithelia: Goblet cells
Goblet cells are specialised for secreting mucus - a mixture of glycoproteins and proteoglycans synthesised in the ER and Golgi.
The mucus is secreted at the apical surface. In the gut - this means the mucus is secreted onto the gut wall, and it helps to protect the cells in the gut wall from the contents of the gut.
Try to identify the goblet cells in this section from the trachea.
Their staining is much paler than the columnar cells.
Why is this?
Notice the specialisations on the top surface of the columnar cells - what do you think these are?