Scale bar represents 10µm
The cytosol fills the space between the plasma membrane and the nucleus embedding membrane-bound organelles and other larger structures such as the cytoskeleton. It makes up about 70% of the cell volume and plays an important role in many metabolic reactions or protein biosynthesis.
The immunofluorescent staining of the cytosol encompasses the whole cell but the nucleus. The staining can vary from smooth to granular, and is often stronger close to the nucleus.
Read more about the proteome of the cytosol.