So let's continue our discussion on the different types of organelles found inside eukaryotic cells. And let's focus on the endoplasmic reticulum and the Golgi apparatus. Now, right outside the nucleus of most eukaryotic cells, and we say most because some eukaryotic cells, such as red blood cells, do not contain the endoplasmic reticulum nor or do they contain the Golgi apparatus. Now, right outside the nucleus of most eukaryotic cells is a network of membraneous faults known as the endoplasmic reticulum, or simply the Er. Now, the membrane of the endoplasmic reticulum is a bilayer. It's a phospholipid bilayer that separates the cytosol portion of our cell with the inside space of our Er.