The majority of the cell's cytoplasm is occupied by mucinogen granules, except at the bottom, where rough endoplasmic reticulum, mitochondria, the nucleus, and other organelles are concentrated.
It primarily modifies proteins delivered from the rough endoplasmic reticulum but is also involved in the transport of lipids around the cell, and the creation of lysosomes.
The rough endoplasmic reticulum is so named because the cytoplasmic surface is covered with ribosomes, giving it a bumpy appearance when viewed through an electron microscope.