1. Nucleoid. It is the open nuclear material of prokaryotes. It is an irregularly shaped region that contains the genetic material of the prokaryotic cell.

2. Eukaryotic cells. The cells in which the nuclear material is enclosed by a definite nuclear membrane are known as eukaryotic cells.

3. Cristae. The infoldings of the inner membrane of mitochondria which look like finger like projections are called cristae.

4. Mitochondrial matrix. It is ground substance present in the space enclosed by the inner mitochondrial membrane. It is also known as nucleoplasm.