The rough endoplasmic reticulum gets its name from:

1. The name records how the organelle looks under an electron microscope. 2. The rough ER carries ribosomes attached to its cytoplasmic surface. 3. Those ribosomes give it a studded appearance when viewed through an electron microscope. 4. The smooth ER lacks them, which is the whole basis of the rough and smooth distinction. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 4 'Cell Structure', sections 4.1-4.6_