Dictyosomes are stack-like structures found in the cells of plants and some protists, serving as a part of the Golgi apparatus. They are involved in the modification, sorting, and packaging of proteins and lipids synthesized in the endoplasmic reticulum. These organelles play a crucial role in the secretion of substances and the formation of cell walls in plant cells. Essentially, dictyosomes facilitate the processing and transport of biomolecules within the cell.