Nuclear membrane

The nuclear membrane (or "nuclear envelope") is the membrane inside a cell around the nucleus. It has the genetic material (chromosomes and DNA) and the nucleolus inside it. The membrane forms a double layer. It is connected to another group of membranes in the cell, the endoplasmic reticulum.
The membranes or envelope is a double lipid bilayerd membrane which surrounds the chromosomes and nucleolus in eukaryotic cells. 
The nuclear membrane has thousands of nuclear pores. They are large hollow proteins about 100 nm across, with an inner channel about 40 nm wide. They link the inner and outer nuclear membranes.
During cell division, the nuclear membrane breaks down to allow mitosis to take place.