What are the main structures within the cell nucleus?



The main structures within the cell nucleus are
(i) The nucleolus which is 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).
(ii) The chromatin, made up of DNA molecules dispersed in the nuclear matrix during the cell interphase.
(iii) The nuclear membrane that delimits the nucleus.