<Li> Smooth endoplasmic reticulum </Li> <Li> Cytosol (fluid that contains organelles, comprising the cytoplasm) </Li> <P> In cell biology, the cytoplasm is the material within a living cell, excluding the cell nucleus . It comprises cytosol (the gel - like substance enclosed within the cell membrane) and the organelles--the cell's internal sub-structures . All of the contents of the cells of prokaryotic organisms (such as bacteria, which lack a cell nucleus) are contained within the cytoplasm . Within the cells of eukaryotic organisms the contents of the cell nucleus are separated from the cytoplasm, and are then called the nucleoplasm . The cytoplasm is about 80% water and usually colorless . </P> <P> The submicroscopic ground cell substance or cytoplasmatic matrix which remains after exclusion the cell organelles and particles is groundplasm . It is the hyaloplasm of light microscopy, and high complex, polyphasic system in which all of resolvable cytoplasmic elements of are suspended, including the larger organelles such as the ribosomes, mitochondria, the plant plastids, lipid droplets, and vacuoles . </P>

What structure separates the contents of the nucleus cytoplasm