So we have an inner as well as an outer region of the membrane that basically looks something like this. So we have the outer membrane region that consists of the hydrophilic heads and the hydrophobic tails. And we have the inner membrane region that also consists of our hydrophilic heads and the hydrophobic tails. And the space, the fluid space between these two regions, the outer and the inner membrane, is known as the perinuclear space. Now, throughout the entire nuclear envelope, throughout the entire nuclear membrane, we have very tiny holes known as nuclear pores that basically allow materials to move into the nucleus as well as outside the nucleus. And we'll discuss exactly what the nuclear pore is in just a moment.