What is "nuclear membrane"

n. A double lipid bilayer that surrounds the genetic material in eukaryotic cells

A nuclear membrane, also known as the nuclear envelope, nucleolemma or karyotheca, is the double lipid bilayer membrane which surrounds the genetic material and nucleolus in eukaryotic cells.

The nuclear membrane consists of two lipid bilayers—the inner nuclear membrane, and the outer nuclear membrane. The space between the membranes is called the perinuclear space, a region contiguous with the lumen (inside) of the endoplasmic reticulum. It is usually about 20–40 nm wide.

The nuclear membrane has many small holes called nuclear pores that allow material to move in and out of the nucleus.