What are the main structures within the cell nucleus?
Within the cell nucleus the major structures are: the nucleolus, an optically dense region, spherical shaped, where there are concentrated ribosomal RNA (rRNA) associated to proteins (there may be more than one nucleolus in a nucleus.
The chromatin, made of DNA molecules dispersed in the nuclear matrix during the cell interphase.
The karyotecha, or nuclear membrane, the membrane that delimits the nucleus.