The smooth endoplasmatic reticulums, ribosomes, vacuoles, lysosomes and centrosomes are among the numerous components of a cell that are not found in its nucleus. All of these structures are located between the nuclear and cell membranes.
A cell's nucleus is separated from the rest of the cell through a double-layer membrane. Most of a cell's organelles are outside the nucleus. Inside the nucleus, there are some specific structures, such as the nucleoplasm and nucleoli. As the nucleus has important DNA functions, it also contains materials used to synthesize DNA and RNA. Eukaryotic cells contain a number of chromosomes inside their nuclei. The nucleus also contains a fluid similar to the cytoplasm that is called nucleoplasm.