And let's begin by discussing what the rough Er is and what the functions of the rough Er are. So the membraneous folds found closest to the nucleus of our cell contain ribosomes embedded on the cytosol side of our endoplasmic reticular membrane. These ribosomes function to synthesize proteins that are ultimately either embedded into the cell membrane. These proteins are known as integral proteins, or they are destined to leave our cell altogether. Now, the membrane of the rough Er is actually physically connected to the membrane of the nucleus known as the nuclear membrane or the nuclear envelope. And for this reason, we see that the perineuclear space, the space between the double layer of our nuclear envelope and the Er lumen, is actually physically connected as well.