Nuclear membrane is an interface between nucleus & cytoplasm which serves to separate the genetic components of the cell (chromosomes) from the protein synthetic machinery (ribosomes & endoplasmic reticulum). These membranes were perforated by many nuclear pores which are the main sites of transfer of macromolecules. Nuclear pores may have diaphragms, septa, annuli, blebs or micropores a central micropores which has nucleoplasmin for the movements of substances. For eg. the mRNA & newly made ribosomes can leave and molecules needed for the manufacture of ribosomes & DNA (protein & nucleotides) can enter.